Theatre of the Mind

Theatre of the Mind

The reason for not using gridded combat and miniatures was that the game was one of imagination. All the technical stuff like rules, gridded movement and so on kicked you right out of that imagination, and out of the flow of action.

No miniatures or grid

Gary never used maps or minis: maps and minis were Dave Arneson’s thing. Gary ran games in his office, which was provided with chairs, a couch, and file cabinets. While playing, Gary would open the drawers of the file cabinet and sit behind them so that the players COULD NOT SEE HIM. They only experienced the Dungeon Master as a disembodied voice. [29]

No, as far as I am concerned miniature figurines are more of an impediment to the imagination required for RPGing than they are a help...save in combat situations. However, as RPGs are not meant to be accurate/realistic combat simulation exercises, the use of miniatures tends to cause an erroneous focus to the play. [11]

We left tabletop miniatures battles behind in favor of the RPG. When mass-combat took place the DMs I played with, as well as me personally, abstracted the battles to contests between the principal figures, did quick attrition of the ordinary forces, and then used morale to determine when one side or the other broke. The reason for that is that the players did not want to wargame thay wanted to engage in RPGing.  [11]

I don't usually employ miniatures in my RPG play. We ceased that when we moved from CHAINMAIL Fantasy to D&D. I have nothing against the use of miniatures, but they are generally impractical for long and free-wheeling campaign play where the scene and opponents can vary wildly in the course of but an hour. #1721

When we began playing D&D all the time nobody cared much about using figurines, we seldom if ever did then, although there was a considerable demand for a D&D line, so eventually Grenadier was granted the license to produce the official line for them, [11]

I am lucky to get a half-hour's prep time, so I use scratch paper and dice on the table top to indicate the position of figures. When all is said and done, the RPG is an exercise of imagination, and no embellishments need be added...although illustrations are most helpful to the GM. [35]

No screen, props, music

I seldom use a screen, but I don't leave notes in view of the players--the map sometimes, but not other written material. #2055

I usually don't use any other props, but once in a while I will slip something in if I think it will liven things up. The exploding scroll tube is a good example of what I mean. #2864

I never use music as it is already quite difficult to manage to speak and retain the players' attention. #8068

Immersion

What I attempt is to have the party behave as would real persons in a confused situation. [11]

Persistence of deeds

After reading a lot about the campaign world and style of the Great Greyhawk and Blackmoor campaigns, I've come to realize that persistence was one of the major implicit ideas that made the game world real: the idea that what happened in play with any group, changed the world for all groups.

The castle, with several groups playing in it [7] was a living thing. If one group slew monsters, plundered treasure or destroyed a wall, the monsters would be dead, the treasure gone, the wall demolished for the others. If you wasted time, some other party might take advantage of you and get to the treasure first. This experience must have made it feel much more a real place to the players, than a typical "adventure" that just provides a story around the characters. You would run into houses or keeps other players had built, could meet them sometimes even as NPCs. 

Hundreds of different players with yet more PCs adventured in city and castle, blasted buildings, created constructions, wiped out walls, closed passages, created new ones, trashed monsters, brought in others, and who can say what else! [15]

James Ward: I didn't find out until years later that Terry Kuntz set up a flunky hiring building in Greyhawk. Characters were constantly looking for flunkies to help in the battles. I hired one of those myself in a dwarf and raised him up to sixth level. Later I found out Terry's characters were hired by others and went back and told Terry about places in the dungeon that were worth raiding. [30.3]

The dungeon, city and rules were constantly changing and expanding. The OD&D rules are chock full of advise how to modify the dungeon [1] to keep things interesting. Gary (and later Rob) generally did not "reset" the dungeon by restocking the monsters and treasures for the next group -- what was gone was gone, but they modified the dungeon constantly by adding new levels, rooms, or changing existing ones or bringing in new monsters in longer-deserted regions.

When the setting was in constant use, we never restocked, just drafted new side and deeper levels, as it was assumed that the depredations of the cruel PC parties kept the monsters away in fear and loathing  [6 #3827]

When the encounter was eliminated I simply drew a line through it, and the place was empty for the foreseeable future. [2]

In later days, Gary ran his first level of the original dungeon at conventions, and his kobolds caused numerous total party kills against players only used to balanced encounters. The kobolds, in a self-reinforcing loop, got stronger from this each time, and even deadlier for the next group. Here is a detail evolution in a post from Gary [17]:

I have run OD&D games every year at several cons for the last five or so years. I start them at 2nd level and use the old dungeon levels. So far about eight parties have been taken out by some kobolds on the 1st level. New RPGers seem to have not learned to run away when in doubt. 
The first to fall used a sleep spell to get eight of the kobolds, but the six remaining ones used javelins to kill two PCs, then closed and in hand-to-hand killed all but two or the remainder of the party. One was about to kill another PC, while a second charged the m-u of the group, who turned to flee, finally. Too late, a javelin got him. Each group that died thus added to the kobolds:

1st TPK brought 12 more kobolds
2nd TPK gave them armor class of 6
3rd (near) TPK gave them all +1 HP
4th TPK added +1 damage
5th TPK added 4 2nd level and 2 3rd level kobolds
6th TPK gave them tactical manouvering and a 4th level leader
7th TPK upped AC to 5
8th TPK gave them unshakable morale

At JanCon this year the Old Guard Kobolds joined battle with a group of 8 PCs and wiped them out. I haven't decided how that will add to their combat ability, but I am considering a kobold shaman with at least two 1st level spells.

Even though in his home campaign, his group of 5th level characters then finally killed the buggers, he argued that this had been an alternate version of the castle, and bringing in the best from history, the Old Guard Kobolds with all the above advantages and with the shaman added show up in the first level of the published Castle Zagyg [7]. Essentially the idea here is the same -- even over years of play: what happened happened, and will be part of the world.

Another example is that the home game group, real-world decades later, found the hidden level where Erac had perished, and revived him. 

In the words of the author of  blog of holding: I’m still not sure what player skill is in OD&D, and I still think it has something to do with battle tactics, trapfinding procedures, and gaming the DM. But I’m also starting to think it has something to do with respecting the gameworld as a world.

Variety for Campaign Longevity

Variety in challenges and activities

Gygax believed the key to an enjoyable game was variety in activities: 

• fights and action ("roll-play"), 
• talk and interaction ("role-play"), and 
• problem solving and exploration 

Fixation on a single aspect of the RPG form makes for tedious play to my thinking. All combat, all exploration, all yakking, all problem solving, all any single thing is downright dull. Balanced play is about half of the favored aspect, with the others having lesser time in the adventure session--sometimes hardly any, although they should then dominate a near-future session. #6459

Forget the business about role-playing. It is as boring as rule-playing and roll-playing are when made the focus of the game. Notice that I stress game, as that's what is the main operative word in the description of the activity. The majority of persons engaged in RPG activity love to go on dungeon crawls, so the ToH was designed to challenge the best of that lot. #2359

As false to the game form as the pre-scripted "story," is play that has little more in it than seek and destroy missions, vacuous effort where the participants fight and kill some monster so as to gain more power and thus be able to look for yet more potent opponents in a spiral that leads nowhere save eventual boredom. So pure hack and slash play is anathema to me too. [36]

What he thought to be a detraction of the fun was

• focus on and arguing over rules ("rule-play")

Over some decades of gaming, the creation of some number of RPG systems, I have come to the point where I prefer a rules-light system [...]. I do not like to rule-play, and as a GM I find long lists of stats and the like tedious. Such things tend to get in the way for my style of play, including as a PC. While I do enjoy plenty of roll-playing (after all I am a military miniatures player too), centering the game on combat seems fatuotous to me. I want a game that facilitates all of the elements of the RPG. #535

Most people enjoy roll-playing and role-playing, but rule-playing is a complete bore #8523

He felt that discussing rules was never enjoyable, and a focus on rules only limited the imagination. It is focused on artificial simplifications that never can do a situation believable justice. It also is less likely to be objectively resolved in a stress sitution for the characters. In my opinion, the best way to resolve these issues is to have the DM make a call, accept it, take a note of it, and research it after the game to agree how to handle it going forward if it comes up again. 

Variety in Adventure Type

There also was variety in the environments -- mixing up dungeon delving with wilderness exploration, with city adventure and intrigue.

Mix up the adventure settings so that play is not always in the same dort of place. A town adventure leads to a wilderness trek, that brings the party to a subterranian setting for example. From there they might have a waterborne or aerial mission.  #6966

Variety in Genre 

Beyond even the kind of adventures, when people got bored with the medieval fantasy he leavened it with adventuring in other genres -- from Science Fiction or Planetary Romance on Barsoom or Vance's Planet of Adventure, to settings inspired by movies like King-Kong, or books like Alice in Wonderland, even to adventures in contemporary New York City. In this, the backdrop stayed the medieval fantasy campaign, but he had about one session in ten with such other environments, to keep it fun. 

Spot in in regards to having PCs adventure in different environments. I believe that keeps them, and the GM alike from growing complacent, or bored. Ernie's PC read a curse scroll and got sent to Barsoon--ERB's Mars, of course.  #1842

Actually, the scope need not be restricted to the medieval; it can stretch from the prehistoric to the imagined future, but such expansion is recommended only at such time as the possibilities in the

medieval aspect have been thoroughly explored. [1, Introduction].

These days, rather than breaking the versisimilitude of the world by doing this, I'd rather just play some other system for variety. In our student days, we alternated D&D with Call of Cthulhu, or Teenage Mutant Ninja Turtles. And even back then there were Traveller, Boot Hill and so on.

Improvisation

Most of the detail in the original Greyhawk Campaign was invented on the spot during play.

From my own experience, I can say that this approach tends to create the most exciting, immersive stories. Some of the best and most memorable adventures with my group were when I just made up stuff in response to their suspicions, actions and to whatever the muse told me. I think this is because when you are not forced to follow and read detailed scripted material, the game flows better, there is no wait times reading up what exactly is in the room, and you are able to focus on whatever the group seems to find engaging most. Of course, once invented, these adventures take on their own reality and become part of the fabric of the world. 

As for making up stuff, that has always been at least 75% of every dungeon adventure I have run that isn't a test of a module meant to be published for public consumption. [11]

I usually made one-line notes for my dungeon encounters, from around 20 to 25 of same for a typical level done on four-lines-to-the inch graph paper--a few more on five-, six, or seldom used 8-line graph paper. the other spaces were empty save for perhaps a few traps or transporter areas and the like.

I did indeed create details for the PC party on the spot, adding whatever seemed appropriate, and as Rob played and learned from me, he did the same, and when we were actively co-DMing we could often create some really exciting material on the spot, if you will.

When the encounter was elimiated I simply drew a line through it, and the place was empty for the foreseeable future. I'd give Rob the details of any session he was not at and vice versa, so we winged all of it. Sometimes a map change and encounter key note of something special in nature was made, but not often. We both remembered things well, Rob very well and when necessary something was made up out of whole cloth for the sake of continuity of adventuring.

When new maps were made it was often nearly impossible to have the stairs and other connections line up with other maps, so a note or two and "fudging" served perfectly well. This was particularly true of the means of entering and exiting lower levels from secret locations surrounding the castle ruins. #4660

Just in case some reader here thinks it odd to create on the fly as Rob and I usuall are want to do:

The main difference between formal creation of material and doing it as one serves in the role of GM is spontaneity, that allowing the material created on the spot to better suit the player group and the situation at hand. Otherwise one must set forth the material to be played and recite it more or less verbatim, forcing the group to its mold. The creative demand is much the same, but the free-style method usually allows for more enjoyment by all participants. I recommend it to all GMs able to manage such playing style #4664

While I do often go with prepared material, especially when I am not feeling really full of energy, the best game sessions are often those in which SOP was in full swing. GMing on the fly is more demanding than is using prepared material, one's own or a published module, but the players generally really get into an extemporaneous adventure, as they are integral to its formation and direction. #4676

SOP, standard operating procedure was to make up stuff "from whole cloth".  

Skim the material, have the map handy, and then, after reading the intro material, some aloud for the players, while remembering the more interesting parts, wing the rest of it. the material is your own when you are running it for your group #6238

Of course most of the long-time DMs will have much experience in winging it even with modules, as that was assumed to be the normal way to run adventures for the first 10 or even 15 years of RPG play.

I suspect that newer GMs are more used to the hand-holding modules, prepare like material for their own campaigns. #4680

The opinions of some folks to the contrary, I have always "winged" most adventures--the exceptions being play-tests of material in a ms. for a module, and a few set-piece places I developed. All the outdoor adventures I ran, and most of the dungeon crawls were half or more made up on the spot. #1706

Most of the time I am GMing something other that a play-test of some module, I wing the whole adventure session, so the palyers are at complete liberty to do whatever their hearts desire. If it is something foolish, I enliven things a bit more than usual...  #6924

I rely on a map for general inspiration, but do not usually have any real notes at all, only pretend ones to make the players think the adventure has been planned. Of course my old-time regulars knew that wasn't the case, especially when they were returning to Greyhawk from the Land of Chin. As well as when dungeoneering, as all of them had seen the encounter notes page for one or more levels, single lines for each of 20 or so places on each level. Dice assisted in that by indicating random encounters, what was encountered...if it fitted. Otherwise I would select the one that seemed right or make up something. #6928

On top of that, EGG and I were both naturally creative individuals whom as co-DMs sought out expansion (and expression) of concepts and ideas as these gathered to us.  These ideas were often spawned during game play, by reading a book the night before an adventure, through scouring our ever-growing notes and sometimes were derived from voiced, but errant, surmises on the players’ parts, such as … “I bet it’s a…”  …or … “It seems like a watcha-ma-jigger” or, more emphatically, “It’s a (fill in the blank for a monster or situation)!” [41]

The level designs and minimal prepared notes provided a framework for the GM to start from. Look at level 1 of the castle for an example. 

Gygax improvised large amounts of content, in response to player actions -- giving them more of what appeard to excite them. He also improvised rules, to keep things moving, rather than looking them up in the book, even where they existed. 

Of course, on the player side of things you would not know what was predefined and what invented, and this approach helped to avoid wasted time looking up what was written in the adventure manuscript and kept the game moving. 

In the original campaign run in Lake Geneva, much of the refereeing was done "seat-of-the-pants" style, and encounter areas were not fleshed out much beyond quickly jotted notes.  [7]

Whatever was there was just to stimulate the DM's imagination and inspire something that suited the party for good or ill. [6]

All the outdoor adventures I ran, and most of the dungeon crawls were half or more made up on the spot. [6 #1706]

Rob and I both DMed on the fly, made only short and often cryptic notes, and thought very much alike, so handing the "castle" back and forth as co-DMs was never a problem. Encounter notes consisting of only one line from which we created reams of information out of whole cloth on the spot. [2]

Rob and I both DMed on the fly, made only short and often cryptic notes, and thought very much alike, so handing the "castle" back and forth as co-DMs was never a problem. The old material would be basically unusable my most others, of course, encounter notes consisting of only one line from which we created reams of information out of whole cloth on the spot; [6 #4414] 

Areas around the city were developed on the spot as the need arose. As a matter of fact, all of the adventures in the City of Greyhawk were “winged”, created from whole cloth on the spot. The many players now active loved this. Even though the castle dungeon levels were deeper, the challenges greater, the rewards richer, proportionally more time was spent in “city adventuring.” [6]

It is so tedious to remember all the minor, but necessary, details. how I do enjoy winging a dungeon crawl with nothing but a map and the sort of encounter noted, creating all the other details on the spot! #2929

In my opinion the best way for a DM to manage monsters is to know what their type is, generaly what an average one of that sort can do, and then...WING IT! #7480

Reacting to Player Action and granting agency

When extemporizing, the GM must be prepared to handle all manner of unexpected actions by the players. If they are foolish, I always invent a number of opportunities for disaster. If the course taken is one that is clever and innovative, I add in rewards.

Before a party goes off on a likley disasterous course I will try to deter them from such action--wandering monsters have much usefulness in this regard.

As for "railroading," there are some scenarios where a bit of that is absolutely necessary to further the whole of the adventure. This is not to say that an entire adventure should be linear and force the party into a situation with a foregone conclusion. The use of a predetermined outcome should be only to set up an interesting and challenging scenario where the players are absolutely free to manage the outcome on their own, that outcome offering penalties for wrong decisions, rewards for correct ones, large rewards for innovation and creative solutions #1706

Incorporating Player Ideas

Gary went beyond just making up missing detail: he was making up the story in response to the players.

Mining the player group for ideas is certainly a good idea, as many heads are often better than one when looking for new and innovative approaches. Of course, that is one of the uses of well-designed modules...fresh ideas slip into one's own campaign. My group always castigates a fellow that mentions something I might do, for they know if it is demanding and I hadn't thought of it, the mention will assure the appearance of whatever was spoken of at some point... [6 #5833]

I would often allow in-game discourse between PCs to develop a plot and direct the general direction of things. Not surprisingly, the players often know pretty well what sort of adventure they would enjoy, so by listening and creating by the seat of one's pants can work wonders...or at least squeek by with something that's mildly entertaining to the group. #287

Of course I am used to winging adventures for a few decades now. It is work when doing so, but it generally is a more enjoyable adventure experience for the players, as one can craft events directly from players' comments and the actions of their PCs. #6916

Outside of the random tables, dungeon components etc. I have prepared over the years, most of which have been published when I wing it I try to suit the adventure to the players and their PCs.

I listen to what the players are saying about the adventure, and take inspiration from chance remarks...as I believe most other GMs are wont to do. #6939

Other than the matter of me doing a good deal of extemperaneous creation in play sessions, I am not a paricularly notable Game Master  [11]

Keeping it up

Gary continued this approach also in later years, during the convention play.

I have indeed DMed a fair number of adventures using other designers' material. The SLAVE PITS series, for one, and another I used often for quick pick-up games was the ABDUCTION OF GOOD KING DESPOT, one of my favorite short scenarios. #1707

Usually, though, players want to adventure in something I have created, so I do a lot of winged adventures outdoors or in the old Castle Greyhawk dungeons, or else use manuscript material I have on hand. To be absolutely truthful, I usually create new material on the spot for my own material that doesn't exactly follow what is written down, as circumstances alter cases :D #1707

Adventure Hooks

I have no standard ones that aren't the usual stock in trade of GMs everywhere. Typically, I inform the team that their renown has reached the ear of so-and-so, thus cuasing that one to want then to do X for him or her. Otherwise, they are assembled because Y threatens them, or they have heard of the fabulous Z and wish to acquire/destroy it. Sometimes, I suggest the adventure is being undertaken because they are bored with the humdrum affairs of the ordinary and seek adventure. Of course, having some friend or relative kidnapped is always a good adventure hook too ;)

Whatever suits the campaign, the players, and the GM's fancy serves as a lead in to the adventure. When I create a module I always try to have the hook included as general as possible so as to be mutable to meet the above. #4415

City Games

A sketch map of the community, a few places of interested highlighted in color, and then wing it. As the PCs develop something interesting by interacting with what I present that becomes a fixture in the town. This might be a particular street thief, a tavern, a stable with a shifty owner, whatever... #8751

[References: see Greyhawk References]

Urd

Map of the Azure Sea is licensed under CC-BY 4.0. 

This is the province of Urd, a home province I wrote for D&D. It shows the idea of zooming in  -- you start with the map, and then flesh out detail as needed, as well as of growing out -- you add additonal  bigger picture context or neighboring cultures as needed. On the Darlene map of Greyhawk, it is located south of Celadon Forest, nestled between the Bright Desert and the Gnatmarsh.

[Players in my Greyhawk campaign: stop reading here, unless you want to spoil your fun of discovery.]

The province is a sleepy backwater that harbors a big secret. Eons ago, a wizard of epic power lived here and forged a ring that granted immortality through godhood. The gods were not pleased, and sent a terrible three-headed dragon to punish the land, which led to the desolation now known as the bright desert, nearby. (No lame scropion crown. That was one of the most disappointing artifacts I ever saw.)

With time, the wizard tired of immortality. He forged a lance tipped with the ring, and a valiant knight, Sir Karl von North, used it to kill the dragon. The ring's fragments were forged into three lesser rings to grant near-immortality to the wizard's sons. Three huge dragons crawled from the corpse of the dragon as a result, and now terrorize the bright desert, the Yortmil Mountains, and the jungles in the far south.  

Sir Karl rammed the lance with the remaining fragment into the rock and fastened his banner to it, and a fountain sprang forth that is said to grant health and long life. Around it the town of Northflag grew. Only a true heir of Sir Karl in free will can pull the lance out.

In the god-wizard's keep, the secrets to re-forging the ring from its fragments still await. Before he died, the wizard gave care of the keep to his apprentice, whose family safeguarded the secret entrance for many generations. A couple of years ago, one of the two sons of that family turned evil and slew his father by collapsing the family tower. The son, now an evil necromancer, wants to reforge the ring to attain goodhood. To this end, he plans to conquer the area with his undead hordes, secure the rings of parts, and manipulate a true heir of Sir Karl for the band. (In the campaign, the players beat back the undead invasion before he could get all the rings, delaying this for now.)

You can tell I like wizard towers, but there is a reason why there are so many here. Three of them are the sons of the god-wizard, two are the two rivaling brothers, one is the ghost of the father. Leaving only one abandoned tower unaccounted for.

I like giving background information and maps to the players. This enables them to find interesting places to explore, in free choice.

• Player Intro
• Campaign secret
• Player Map
• Master Map 
• Random Encounters & Holidays
• Province Knights
• Northflag Map (Main Town)
• Town Cathedral and patriach
• Town Mage
• Town Traders
• Town Crime Scene
• Thorp of Urdingen
• Druid Grove 
• Village of Furton (from Beyond the Glittering Veil)
• Leuchos' House (original scribble notes)
• Winterland* Extra-Dimension
• Hamlet of Anforst (Luskwald from Redacap's Rampage, Dungeon #54)
• Player Map
• Master Map
• Extra NPCs
• Chapel  in woods with secret tunnel to ruins
• Village of Walden (or Buhr Ailgra, Delminster from Horror's Harvest, Dungeon #38)
• Forest of Urd
• Entry to Underdark (from Witches Fiddle, Dungeon #54)
• Abandoned Mage Tower
• Keep of Sir Macelot (region's abducted feudal lord)
• Towers of the Brother (in perpetual winter)
• Tower of the Wizard of Urd
• Mad Mage of Charburner Rock
• Ruined Ghost Tower
• Margarethe's Cottage
• Old Mill
• Ghost Mountains
• Goblin Peak (NPCs, background)
• Map
• Map Goblin Town 
• Mount Hammer (NPCs, clans, history)
• Map Old City
• Ventilation Shafts
• Key and random encounters
• God-Wizard's Keep at Sorcerer's Pass
• The dream jewels of Utnampitschi
• Taxes 
• Traveling Circus 

Growing out of the province

• Bert, the hill giant (wandering the hills to the West and South)
• Map of the Great Magic Forest (Southern Celadon Forest, to the North)
• Hut of the Little Witch
• Ruins (from The Seventh Arm, Dungeon #88)
• Entry to Underdark Map (from Headless, Dungeon #89)
• Druid Cave (from Hunt for a Hierophant, Dungeon #63)
• Encounter with Sir Karll von Urnst, hunting (from Greyhawk adventures)
• Map of Hills and Hillsport (to the South)
• Monastery of Montenegro (from Unhallowed Ground, Dungeon #54)
• Wild Boar Inn (werewolf detective adventure)
• Crypt in the Hills*
• Necropolis (not detailed yet)
• Palace of the Twisted King, Dungeon #116 on the road south
• Hillsport (Scalabar from The Scourge of Scalabar, Dungeon #74)
• Vampire Adventure (with Old Captain's house, Villa, Ship, Island, Vampire Castle etc.)
• Villager's safety cave for Sahuagin raids
• Pirate Beach and Pirates
• Map of the Bright Desert (to the West)
• Vassar Desert Elves
• Sighting of Zaxxar, Curse of the Bright Desert (Ancient Blue Dragon)
• Old Sepron & Telar Ruins (from Telar in Norbia, Dungeon #31)
• Omt (Athkatla from Thirds of Purloined Vellum, Dungeon #88) 
• Oasis of Khaldun & Valley of Mists (from Blood & Fire, Dungeon #63)
• Map Gnatmarsh (to the East - nobody goes there due to the Necromancer)
• Tower of the Necromancer (with surrounding swamp, NPCs, etc.)

Growing out of the region

• World Map (I used the Darlene Map)
• Player World Map - Nyr Dyv
• Major Religious Faiths in the region
• World Design (concept of culture spheres and growing out)

This area served as home turf for several groups of adventurers, the first assembled from accross the province, the second from Northflag, the third from Walden, the fourth from Northflag again. The tax calculations were added, as some players came from one of the noble families (Sir Herman von North, the son of the missing lord among them). 

The town cathedral was an example of unneeded effort. As there was no adventuring in its crypts, there was no point to create the floor plans in the first place (but I was on vacation in Navarra, Spain at the time, with many wonderful examples of Cathedral architecture). The same was true for the druid grove. Goblin Town is still waiting to be played, as is the final assault on the tower of the Necromancer, and the keep of the god-wizard (to which you ascend through a number of pocket dimensions with altered rules, similar to the tomb in desert of desolation). As none of the groups even came close to getting to the keep, I never worked that out.

* There was a side story of an evil overlord who had been defeated long ago, with his generals entombed as major undead in seven crypts, waiting for his return, guarded over by an old order of druids. I placed one of the crpyts and the wintery dimension where the evil overlord was jailed away in a chest hidden on an attic in one of the villages. The only other crypt worked out was the one where that backstory came from, the beer adventure. One more crypt was put into the rolling hills. I handed the players a treasure map in two pieces found in different places, that allowed them to put it together and locate the crypt (see above). They found it, but the gorgon at 4. petrified the wizard, and at that point they had enough of it and beat a retreat.

Random Monsters vs Monster Lairs

I love random encounter tables, as a concise way to describe an area and its inhabitants. 

"Monster Lair" is licensed under CC-BY 4.0. 

The creatures encountered will normally have a base of operations nearby, commonly called their lair. Often in that lair, a larger number of them will be encountered, with surplus treasure, far more than what the wandering creatures carry. 

For beasts, vermin, or oozes, this may be a lair proper, where they are sleeping or nesting, with treasure from carcasses of their victims. For undead it may be a crypt, grave or sepulchre, where treasure has been laid to rest with them. For intelligent creatures like bandits or orcs, there will be a hideout, den or fort. 

When the wanderers are patrols, scouts, scavenging parties or on some errand from that lair, by talking with them or capturing and questioning them, the characters can learn about the environment, about factions in the area, and -- if they can charm, pressure or trick them, or secretly track them -- about the location of their lair and treasure. All this is good.

Do you remove encounters from the list, once encountered and killed?

Normally, the answer is no. There are three situations.

Most commonly, encounters are from a large enough pool of creatures, to be not affected by losing a couple of individuals, even repeatedly. Say, wolves in the forest: in the real world, a pack of wolves needs about 14 square miles to hunt, a bit under 4x4 miles. It is quite conceivable that in a small forest that is only a days March in each direction (24 miles), there might be three dozen wolf packs. While you could eliminate them all, encounters tend to be rare and varied enough that you will not kill more than a couple, so it is a fair enough approximation to ignore that. 

On the other end of the sprecturm, sometimes, the tables list unique creatures, for example a dragon living in that forest. For those, the practice is of course to ingnore the encounter if it is rolled again, treating it as either a non-encounter (most commonly), or replace it with a more common encounter result, e.g. by rerolling. If these unique cratures are killed, their lair will be found empty. 

Both of these cases are simple, and straightforward.

But what to do when the encounters come from a limited number of creatures? Do you remove creatures from the lair, and stop encounters when they all are removed? 

For example, assume in your dungeon contains a lair of troglodytes, six total. And on your random encounter table you have this line:

1-2 troglodytes -- renewing sacred wall drawings to ward off spirits

What happens if the PCs encounter and defeat two troglodytes? Will there be only four left in the lair, or all six? How to explain a neverending stream of troglodyte encounters, when the lair can house only six, and has pallets for only six? If the PCs over the course of their explorations run into multiple trog encounters and kill more than six of them, will still be six in the lair? (Mathematician's joke: there will be negative troglodytes in the lair.)

What speaks for removing the killed monsters from the lair? It increases verisimilitude.

(1) It forces you to respect the game world as a real place with inhabitants, not just a generative procedure for staging fights. It makes it more believable. 

(2) It encourages you to think about how the monsters would react. For example, the trog patrols try to escape from the PCs to alert their tribe, instead of fighting to the death; once alerted, the tribe goes after the PCs en masse or stops patrols to lay an ambush. 

What speaks against removing the killed monsters from the lair? Its more work.

(1) Tracking the losses poses a slight administrative overhead for the DM. I think it would not be that hard to cross out the total on the map or key and scribble in a lower number after such an encounter, but is is just one more thing you have to keep track of.

(2) You need to adjust the encounter tables. Otherwise, if there is no response and random encounters continue unchanged, then the characters can use this tactic to bleed out the lairs in a controlled manner. This is even more work.

I confess I often use random encounters as an unending source of monsters. Convenience first. Maybe add a few more pallets to the lair, to make up for it. 

One interesting idea could be to allot a pool of wandering monsters to each encounter in the table. These represent the share of each faction that is typically out and about and thus not reflected in the lair, although they should have some living space there. One would still be able to plan organized responses with the monsters from the lair, but could continue to run the encounters unchanged, until the pool has been used up. Just put the wanderer pool behing the line in the table, like so

1-2 troglodytes -- renewing sacred wall drawings to ward off spirits [total 4]

In cases like wolves in the forest ignore the pool.  In our example, 3 trogs were already killed in two earlier encounters. The last encounter would either be with a single trog, or you would remove one trog from the cave, if two were indicated. And after that, ignore the trog encounter when you roll it, as the rest of the group is huddling up in their cave and not sending more patrols to die. 

This also conserves special characters in the lair (e.g. shaman, seargeants, concubines), that would not appear in a random encounter group normally, and ensure they will be encountered. Although, it might be more intersting to include one of them in the wandering group as leader, especially if the groups of wanderers are larger.

PS In OD&D, the number of creatures encountered in a random wilderness encounter could be huge, especially for bandits or humanoids, and if rolled from a general table would act to define what lairs were nearby, on the fly. The number encountered in a pre-designed dungeon or cave is much smaller, typically 1-6, maybe more if they are especially weak individually. 

Early D&D Dungeon Design Guidelines

OD&D

Because these guidelines came directly out of the playtest campaign in Greyhawk Castle, we can safely assume they reflect the principles and play experience from that dungeon and campaign, and use them to infer what it may have looked like and been like. 

Before it is possible to conduct a campaign of adventures in the mazey dungeons, it is necessary for the referee to sit down with pencil in hand and draw these labyrinths on graph paper. Unquestionably this will require a great deal of time and effort and imagination. The dungeons should look something like the example given below, with numerous levels which sprawl in all directions, not necessarily stacked neatly above each other in a straight line. [1]

In laying out your dungeons keep in mind that downward (and upward) mobility is desirable, for players will not find a game enjoyable which confines them too much. On the other hand unusual areas and rich treasures should be relatively difficult to locate, and access must be limited. The layout of a level will affect the route most often followed by players. Observation of the most frequently used passages and explored rooms will guide the referee in preparation of successive levels, which, of course, should be progressively more dangerous and difficult. [1]

In beginning a dungeon it is advisable to construct at least three levels at once, noting where stairs, trap doors (and chimneys) and slanting passages come out on lower levels, as well as the mouths of chutes and teleportation terminals. In doing the lowest level of such a set it is also necessary to leave space for the various methods of egress to still lower levels. A good dungeon will have no less than a dozen levels down, with offshoot levels in addition, and new levels under construction so that players will never grow tired of it. [1]

Maintaining Freshness: As monsters inhabiting the rooms, spaces, and corridors of a level are killed or captured, the level will become drab and dull. Coupled with this problem, players will have made fairly accurate maps of the level, so it will be challengeless this way also. Remembering that egress to lower levels is desirable, one must nevertheless revamp worn levels by one or more of the several methods suggested below:

1. Make minor alterations with eraser and pencil, blocking passages, making new ones, dividing rooms, and filling in others. 
2. Extend the boundaries of the map, if not already filled to the edges of the paper, adding corridors and rooms.
3. Replace monsters in new areas as well as those less frequented old areas where monsters were located and removed sometime previously.
4. Reverse directions on the map, carefully relocating ways down to lower levels so as they still correspond to markings below, and do the same for passages upwards.
5. Add a passage which continues past the established boundary of the level, creating a split or sub-level which it leads to, complete with new treasure and monsters.

Using these suggestions, and whatever else you dream up, there is no reason why participants in the campaign should not continue to find mystification, enjoyment, excitement, and amusement in the challenge of the myriad passages of the dungeons. [1]

Secrets of a Well-Designed Dungeon

When asked what the secrets of a good dungeon were, he said:

Just that, secrets:D

Tongue-in-cheek as that may be, it matches his statement that "the best part about mysteries is keeping them that", and his lifelong unwillingness to disclose the secrets of the jeweled man or the Great Stone Face. Nearly any resolution for such a mystery, would be a let-down and a disappointment. (I also suspect there may not have been any answer at all, like with some of the mysterious noises: the whole point was to get the players wonder and scheme. An answer was not needed.) Keeping the mystery alive was better than solving it. He continued:

I believe that the first quality a dungeon needs is game logic and verisimilitude based thereon. That's why I subsumed the maze beneath Greyhawk Castle had been created by a mad demi-god [as they made no sense based on any logic or ecology]. The elements needed thereafter are: 

• Challenge of exploration, 
• increasing danger including actual PC loss, 
• varied problems, 
• varied environments, 
• occasional humor or like relief from the tension normal to the environment, 
• mysteries, 
• rewards commensurate with the challenge overcome, 
• a series of milestones indicating achievement in the course of delving into the labyrinth, and 
• a finally where the successful PC(s) get the big reward for staying the course and reaching the untimate conclusion. #1299

This matches the "gain an instant level and +3 equipment" for making it down to Zagyg, the deadliness of play in the OD&D campaign, the extraplanar levels, and the secrets about the jeweled man or great stone face of Greyhawk, or mysterious sounds. 

Design of Greyhawk Castle

When new maps were made it was often nearly impossible to have the stairs and other connections line up with other maps, so a note or two and "fudging" served perfectly well, this was particularly true of the means of entering and exiting lower levels from secret locations surrounding the castle ruins.

I have laid out a new schematic of castle and dungeon levels based on both my original design of 13 levels plus sideadjuncts, and the "New Greyhawk Castle" that resulted when Rob and I combined our efforts and added a lot no new level too. From that Rob will draft the level plans for the newest version of the work. Meantime, I am collecting all the most salient feature, encounters, tricks, traps, etc. for inclusion on the various levels.

So the end result will be what is essentially the best of our old work in a coherent presentation usable by all DMs, the material having all the known and yet to be discussed features of the original work that are outstanding. .I hope :uhoh: [2]

Overall design of the levels

Each level should have a central theme and some distinguishing feature, i.e. a level with large open areas swarming with goblins, one where the basic pattern of corridors seems to repeat endlessly, one inhabited by nothing but fire-dwelling or fire-using monsters, etc. [3]

As each level is finished the various means of getting- to lower levels must be keyed and noted on the appropriate lower levels , so that if a room sinks four levels it will then be necessary to immediately show it on 4 sheets of graph paper numbered, so as to indicate successively lower levels. A careful plan of what monsters and treasures will be found where on each level is also most necessary, and it can take as long to prepare as the level itself, for you may wish to include something UNUSUAL (a treasure, monster, and/or trick or trap not shown in D&D) on each level. [3]

Being of insidious nature, I varied the maps for levels of the castle dungeons. Sometimes I used 8.5" x 11' paper, 4 squares to the inch, sometimes 5, 6, or 8. then I'd throw in two or more levels on the same map, or use 17" x 22" paper with 4 or 5 squares to the inch. At least one level was done with small hexagons. Also, many of the levels were connected so that it was difficult to know when one was leaving one and entering another. [6 #1296]

Early D&D Dungeon Stocking Guidelines

These guidelines are from the time of the original campaign or shortly thereafter about how to stock a level map of a dungeon.

1974 OD&D Vol 3. "As a general rule there will be far more uninhabited space on a level than there will be space occupied by monsters, human or otherwise [...] It is a good idea to thoughtfully place several of the most important treasures, with or without monstrous guardians, and then switch to a random determination for the balance of the level. Naturally, the more important treasures will consist of various magical items and large amounts of wealth in the form of gems and jewelry. Once these have been secreted in out-of-the-way locations, a random distribution using a six-sided die can be made as follows: A roll of a 1 or 2 indicates that there is some monster there. [...] Roll again for every room and space. A roll of 1–3 in those rooms or spaces with monsters in them indicates some form of treasure is present. A roll of 1 in a room or space which is unoccupied indicates that there is some form of treasure there". 

Unguarded Treasures should be invisible, hidden behind a secret door or under the floor, locked in hard-to-open strong boxes with poison needles or deadly gas released when they are opened. (There are many variants of the above possible, and many other types of protection which can be devised.)

This results in about half the rooms being entirely empty, a bit less depending on how many special / unique encounters are placed. This original guidance is very similar to the later Moldvay Basic guidance from 1981: "Special monsters should be first placed in the appropriate rooms along with special treasures. The remaining rooms can be stocked as the DM wishes. If there is no preference as to how certain rooms are stocked, the following system may be used. d6, 1-2: monster, 3: trap, 4: special, 5-6: empty. Treasure d6,  1: yes, 2: if monster or trap, 3: if monster, 4-6: none."

Dungeon Geomorphs "Approximately 25% of the rooms and large spaces should contain monsters, treasures and other notable items. For every five such rooms there should be approximately one trap. Slanting passages, teleportation areas, slides and the like should be added sparingly thereafter -- one or two such items per level is a fair guideline". This has even a lower share of rooms with anything in them, about 60% of the rooms would end up empty.

Dungeon Geomorphs maps from 1976-77 are drawn in the "old" style and the instructions recommend that "approximately 25% of rooms and large spaces should contain monsters, treasure, and other notable items," even the early AD&D modules (G series, T1) and the sample dungeon level map in the DMG are in a very different style -- a lot more black space, a lot fewer rooms overall (the DMG sample level map has 38 numbered areas, several of which are more sections of hallway than rooms or chambers, and the dungeon level map in G1 has 33;  G1 has only 6 of 33 empty rooms -- less than 20%; about the same ratio as the moathouse dungeon in T1 which has 3 out of 18 empty rooms) and a lot fewer "maze" elements ("nested" rooms & corridors, long dead-end hallways, "nexus" points with lots of potential exits, etc.). At some point Gygax seems to have simply decided that he didn't like the maze-navigating aspect of early D&D. [...] The Storerooms map in CZ is consistent in style with pretty much every dungeon map Gary Gygax drew from 1978 on. (T. Foster Analysis)

Solo Dungeon Adventures, An article by Gray Gygax originally published in The Strategic Review Vol.1 No. 1 Spring 1975, has random room generation. It also has tables to populate them: d20 1-12 empty, 13-14 monster, 15-17 monster and treasure, 18 special or empty, 19 Trick/Trap, 20 Treasure. While Gygax said that he did not use it, as he found it faster to make stuff up, he expressed that this generated dungeons close to what he had in mind. Again, about 25% chance for a monster, and 60% empty rooms.

Gygax own Module B2, Keep of the Borderlands is likely the most played module of all times as it was included with the most sold version of the game. It  taught a generation of GMs by example how to design and populate a dungeon and had a much lower rate of empty rooms, only 11% of the rooms did not contain a monster.

From my own experiments, if one pre-populates some unique and interesting encounter areas as suggested, and then only uses the random determination for the remainder, fudging here and there to make things work, and filling some empty rooms with dungeon dressings, the OD&D / Moldvay system works pretty well. And the random placement of non-sensical monsters can be used to spur creative stories and explanations for it, so it makes sense. The latter is actually intense work.

Delta has a fantastic analysis of all of Gygax's own modules. According to this, Gygax real ratios were out of 6: 2 Monster, 1 Monster with Treasure, 1 Treasure, 1 Trick/Trap, 1 Empty. Unguarded treasure typcially was hidden or trapped, as advised above. 

Random Monsters 

The Making of Original Dungeons and Dragons offers a facsimile copy of the orginal D&D manuscript that Gygax wrote between April and May, 1973. It includes the following Encounter tables (p. 110, stating to use "Die", obviously, d6)

Level Beneath  Level of Monster

the Surface    1    2    3    4    5    6

    1          1-2  3-4  5    6    -    -

    2          1    2    3-4  5    6    -

    3          -    1    2    3-4  5    6

   4-5         -    -    1    2-3  4-5  6    

   6-8         -    -    -    1    2-3  4-6

   9-11        -    -    -    -    1    2-6      

    12+        -    -    -    -    -    1-6

This map is with very slight deviation what shows up in the final, published rules (only for level 9-11, the split there is 1-2 and 3-6 for monster levels 5 and 6).

The monster lists however were more in flux. They show multiple edits, and also are more complex than what was finally published, all using only d6 to determine the type, but in exchange, often two layers of rolls. These appear on p. 111f. [Typos fixed, there are no "Gaint Rats" etc., Layout rearranged for readability]

MONSTERS

                      Level 2                          

Level 1  Die          Die 1-3        Die 4-6    2nd Die

Goblins    1          Hobgoblins     Gnolls         1

Kobolds    2          Skeletons      Zombies        2

Bandits    3          Ghouls         Theurgists     3

Orcs       4          Lizards        Spiders        4

Giant Rats 5          Anti-Swordsmen Giant Ants     5

Centipedes 6          Roll again     Roll again     6

                      Level 4                               

Level 3        Die    Die 1-3       Die 4-6            2nd Die

Thaumaturgists 1      Anti-Heroes   Anti-Swashbucklers   1

Anti-Warriors  2      Giant Snakes  Salamanders          2

Wights         3      Wraiths       Ogres                3

Giant Hogs     4      Lycanthropes  Gargoyles            4

Giant Toads    5      Giant Weasles White Apes           5

Giant Crabs    6      Evil Priests  Magicians            6

Keep in mind that in OD&D, giant varieties of animals were a lot more dangerous than in 5e, compared to other monsters in the roster, so the giant hogs, toads and crabs that today are - for the toad example - a measly CR 1 used to be as dangerous as the other denizens of the list, a Thaumaturgist being a level 5 Wizard; a Warrior however was a mere Level 2 Fighting-man. The "Anti-" just expresses that they were opponents, these are not a separate class with distinct features like in later editions the "Anti-Paladin". Evil Priests are likely the opposite number of "Village Priests", i.e. level 3 clerics, Anti Heroes are level 4 fighters, anti-swashbucklers are level 5 fighters, and Magicians are level 6 wizards. 

Level 5                1st Die                    

2nd Die  Die 1-2        Die 3-4     Die 5-6       

1        Trolls         Spectre     Anti-Myrmidons

2        Giant Beetles  Ochre Jelly Giant Scorpion

3        Cockatrice     Gorgon      Mummy

4        Enchanter      Warlock     Medusa

5        Hydra of 5     Hydra of 6  Hydra of 7

6        Roll again     Wyvern      Roll again

The wyvern origianlly also was a "roll again", and then in revison got moved here from the level 6 monsters. The hydra heads also were adjusted, from 4, 5, 6, to 5, 6, 7.

Level 6                    1st Die                             

2nd Die  Die 1-2            Die 3-4          Die 5-6           

1        Black Pudding      Anti-Superheroes Anti-Lords

2        Wizards            Necromancers     Sorcerers

3        Baskilisks         Chimera          Invisible Stalkers

4        Evil High Priests  Vampires         Purple Worms

5        Minotaurs          Giants           Dragons

6        Manticora          Hydra of 8       Hydra of 9

Its noteworthy that there is a lot of editing in pencil going on here, for example, the Black Pudding first was an Anti-Champion, and all second die 6s originally were Dragons. The 5-6 column for the first die included Wyverns for a 3 originally, and when these then were moved to monster level 5, this was shifting everything below one die pip up, so the dragon moved to 5. Then, all the 6s first were replaced with a hydra, of 7,8,9 heads, only for the 7-head hydra then to be moved to level 5 monsters too, when all the hydras there were upgraded, and the freed-up slot being replaced with Mantircora. It seems therefore doubtfull if exactly these tables were really the ones used in Castle Greyhawk, and more likely it originally were the versions that had dragons all across, but this also evolved over time, as new monsters were introduced. 

Also this original draft still included the crucial information how many monsters one would encounter, which dropped in the published version:

Number of Monsters Appearing:

If the level /below the surface corres[p]onds to the level of the monster and the adventurers concerned also equal this level, then roll one 6-sided die (level 1-4 monsters) or one 4-sided die (level 5-6 monsters) for the number which appear (referee's option: only one mosnter can appear without roll). However, Level 1 monsters should usually appear in numbers from 2-12 to 2-24. If the level below the surface or the level of adventurers are signficiantly higher, then multiply the number of monsters accordingly. 

OD&D on dungeon Lists: d6 to determine List to roll on

Level List 1        2        3        4        5        6

1                1-2    3-4    5        6
2                 1      2        3-4    5        6                               
3                         1        2        3-4     5        6
4-5                                1        2-3    4-5     6
6-7                                           1      2-4      5-6
8-9                                                    1-2     3-6
10-12                                                1        2-6
13+                                                              1-6
As Delta observes, this is very deadly, it would be better squish the ranges so the first three rows do not extend into their last listed category. You could run into dragons and vampires on level 3 here...

1. (d8): kobolds, goblins, skeletons, orcs, giant rats, centipedes, bandits, spiders
2. (d10) hobgoblins, zombies, lizards, gnolls, thouls, ghouls, berserkers, F2, W3, W4.
3. (d10) wights, giant hogs, giant ants, ochre jelly, giant snakes, and giant weasels, F4, F5,  W5, W6
4. (d10) wraiths, ogres, giant beetles, giant scorpions, lycanthropes, gargoyles, white apes, F6, C4, W7
5. (d12) trolls, wyverns, spectres, mummies, minotours, manticores, cockatrices, wyverns, hydra 6-8 heads, medusae, F8, W9, 
6. (d12) giants, hydra 9-12 heads, dragons, basilisks, gorgons, chimeras, vampires, spectres (really: balrogs), purple worm,  F9, C9*, W11*

*Typically each will be accompanied by from 1–4 apprentices (Enchanters/Evil Priests) and 1–6 body-guards (levels 4–6) fighter-type.

Other monsters to consider, depending upon the level and the surroundings: Giant Crabs, Giant Leeches, Giant Octopi, Crocodiles, Giant Squids, Sea Monsters,Nixies, Mermen, Griffons, Pterodactyls, Rocs, Invisible Stalkers, Cyborgs, Robots, Androids, Shadows, Dopplegangers

Number of Wandering Monsters Appearing: If the level beneath the surface roughly corresponds with the level of the monster then the number of monsters will be based on a single creature, modified by type (that is, Orcs and the like will be in groups) and the number of adventurers in the party. A party of from 1–3 would draw the basic number of monsters, 4–6 would bring about twice as many, and so on. The referee is advised to exercise his discretion in regard to exact determinations, for the number of variables is too great to make a hard and fast rule. There can be places where 300 Hobgoblins dwell. 

Replace Specter with Balrog in the last chart if your copy of the rules if from after the Tolkien estate forced TSR to remove direct Lord of the Ring references.

Since everything in OD&D except saving throws and attack rolls which used d20 was based on a d6, a consensus good default would be 1d6 for each type of monster of a table matching the dungeon level, so 1d6 hobgoblins on level 2. Most people also double the number with each level deeper, so 4d6 goblins woudl be an encounter for level 3.

Supplement 1: Greyhawk upgraded that to (bold are additions)

1. (d12) kobolds, goblins, orcs, skeletons, giant rats, centipedes, bandits/berserkers, spiders, stirges, dwarves/elves, gelatinous cube
2. (d12) hobgoblins, gnolls, zombies, ghouls, F2s,, W3s, W4s, T3s, T4s, giant toads/ants, bugbears, carrion crawler, removed berserkers to level 1, thouls, lizards
3. (d12) wights, F4s, F5s, W5s, W6s, T5s, T6s, harpies, wererats, giant snakes/spiders, giant weasels/hogs, ochre jelly remove ants
4. (d20) doppleganger, wraiths, gargoyles, ogre, C3s, F6s, W7s, T7s, shadows, giant beetles, giant scorpions, lycanthropes, carnivorous apes, owl bears, displacer beasts, blink dogs, phase spiders, giant ticks, will'o wisps, rust monsters; remove white apes
5. (d20) trolls, ogre magi, F8/Paladins, wyverns, spectres, mummies, druids, hell hounds, invisible stalkers, minotaurs, manticores, lammasu, cockatrices, W9s, W10s, T10s, salamanders, hydra 6-8 heads, umber hulks, giant slug;  remove medusae
6. (d20) giants, titans, hydra 9+ heads, dragons, golems, basilisks, gorgons, fire-breathing hydra, chimeras, vampires, hell hounds, F9/Paladins, efreet, beholders, evil high priests, W11s, T11s, lich, purple worm, rust monsters

Monsters

• Mimicry Monsters that appear as something else (harmless animals, rock, ochre jelly looks like Ogre, grey ooze like snake, black pudding like giant spider);
• Modified monsters (fire resistant mummies, skeletons that can hurl fingers like bolts, multi-headed giant that cannot be surprised);
• Monster combos (Medusa with Basilisk and cockatice pet, riding a gorgon; efreeti riding red dragon with salamander servants; frost giant riding white dragon; troll with magic spear on purple worm, ogre-mage on manticore, wizard with hell hounds, lord riding wyvern, evil high priest on chimera, thieves with bugbear guards, cloud giant riding a T-Rex, hero elf on lammasu)

Tricks and Traps 

OD&D: The fear of “death,” its risk each time, is one of the most stimulating parts of the game. It therefore behooves the campaign referee to include as many mystifying and dangerous areas as is consistent with a reasonable chance for survival (remembering that the monster population already threatens this survival). For example, there is no question that a player’s character could easily be killed by falling into a pit thirty feet deep or into a shallow pit filled with poisoned spikes, and this is quite undesirable in most instances.

Mapping Confusion

• Dead ends
• Sliding Walls, Blocks, rotating floors
• Diagonal passages that are difficult to correctly map
• Natural Caves and Caverns with varying width, direction that are near impossible to map
• Teleporters / Transporters (intra- or inter level), one way or two-way
• Space distortion corridors or stairs, sliding rooms
• False doors
• Secret Doors; one-way secret doors (only open from one side), two-way secret doors (depending how you open lead to two different areas); often as escape hatch for evil NPCs or bosses.
• Locked doors or stuck doors [all doors were swollen/hard to open by default, opening normally for monsters, another item that strains credibility]
• Doors that open only from one side; intermittently; for certain classes, alignments, monsters, with password; that allow traffic only in one direction, have (malign) intelligence
• Stairs up or down, Slides down, Stairs turning to slides (with monster at end), Chimneys / Shafts, False Stairs, Collapsing Stairs
• Steps which lead up a short distance, but then go downwards for at least two levels, with the return passage blocked by bars or a one-way door
• Elevators / Sinking Rooms (one or more levels up or down); fake elevators (appear only so)
• Slanting passages (lead players unwittingly onto another level), also combine with elevators, stairs [Note that this is a stupid feature that would not work. To have a decline that is imperceptible, these passages would need to be miles long]. 

Traps

• Pit traps, open, covered, with spikes, with poison spikes, closing, with secret door inside them, and then other traps behind those..., with teleporters
• Arrow/Spear traps, maybe poisoned
• Pendulum, ball, scythe or blade traps
• Gas, obscuring vision, blinding, sickening, weakening, slowing, deadly poison; inducing sleep, fear, confusion, memory loss, or strength
• Vents spewing acid spray, fire, gas
• Portcullises, falling blocks, collapsing ceiling
• Room traps: ceiling lowers to crush, flooding, floor collapses
• Magical curse room trap: illusion, mind-control, greed-inducing or geas
• Lightning bolt (interestingly, no explosions or fireballs!)
• Vegetation that holds, entwines, moves, flails with branches, makes noise, hurls missiles, or emits dangerous gases

Wondrous Items to muck around with

• Pools: random permanent stat increase/decrease, talking/oracle, transporter/teleporter, converting coins; granting wish; benefits often limited to once.
• Statues that do nothing, point somewhere, recite a meaningless poem, a clue or riddle, shout alarm, offer a real or false map, attack, attack and pursue etc.; Status with a missing piece that activate once it is found and replaced (to do the above or serve for a time)
• Levers, buttons, dials that damage mover, teleport, release traps or that give access to treasure, boni, items or open (secret) doors, pits or slides somewhere
• Cursed items, that cause bickering, attract monsters, shrink, reduce alertness
• Objects that change user or mover (stats, class, alignment, into monster, gender, level, mind)

In the DMG he realized you can really combo any object and magical effect and so listed first features (altars, arches, idols, fountains, pools, rooms, statues etc.) and then possible effects, like the ones listed above, plus: ages, animated, anti-magic, appears, disappears, asks, disintegrates, enlarges, reduces, shocks, petrifies, polymorphs, varies gravity, acts randomly, releases treasure, suspends animation, takes/steals, etc.

Hidden Treasure

• False bottom or hidden compartment in chests and cases 
• Invisible treasure
• Treasure is part of a monster (in gullet, valuable fur, tusks, embedded treasure in horns, claws hide)
• Force Fields protecting treasure 
• Maps (in a world of labyrinthine levels, quite useful), false maps...

Specific items from Greyhawk 

• Wishing well, grant a wish based on value of item tossed in - some just harbor a horrible monster
• The Living Room: Furniture comes to live and attacks wrapping, smothering, kicking, tripping
• The Great Bas-Relief Face: gives knowledge or increase, or save to not become a pimple on it (really Grazz't bound)
• Magic Item Forge with ultra powerful smiths, that sell at steep prices, no guarantee to work
• Hall of Gambling great items can be won but buy-in stakes are high, and the game is fixed
• Room that are the innards of a huge monster (mouth, stomach, intestine)

5th Edition Dungeon Stocking in comparison

5e Appendix A actually conserves most of the tables from the 1e DMG, and has quite detailed procedures to generate content. Why is nobody using that - it looks great? Probably because, compared to back then, now there are more than enough fleshed out dungeons. There is even a random dungeon generator at Donjon, that allows you to create 5e dungeons using these rules at the click of a button.