I followed James Maliszewski’s guidelines when I made Slime Bugs for my Mutants & Mazes campaign. I have failed to follow some of his insightful suggestions ever since, but on creating that adventure I learned a good deal of stuff that I have used ever since.
These are James’s guidelines, I steal them from Grognardia and put them here for quick reference. [I’ll add a few comments between square brackets.]
- Environmental hazards — slippery floors, rooms that flood, narrow ledges over steep drops, rooms that are excessively hot or cold, rooms or corridors filled with poison (or otherwise magical) gasses, etc.
- Combat encounters should generally be with baseline (or near-baseline) monsters with difficulty enhanced by the circumstances of the encounter (i.e. monsters have set up ambushes, monsters forcing the PCs to fight in unfavorable surroundings, teams of similar (or dissimilar) monster-types working together, etc.) rather than through templates or class-leveling.
- At least one encounter that if played as a straight combat will totally overmatch the party, but which can be avoided or circumvented by some clever means.
- At least one puzzle, trick, or obstacle that requires the players to figure it out, rather than being solvable by a die-roll. [If they can’t solve the puzzle the adventure should not stop, there whatever is beyond the puzzle should not be essential to complete the dungeon; alternatively, allow a roll but only after they have tried and failed. Also, add clues scattered through the dungeon, including one in the same room the puzzle is.]
- At least one item, location, or creature that causes some kind of significant permanent effect (permanently raise/lower stats or hp, permanently change race, gender, or alignment, permanently grant or take away magic items, etc.) determined by a random roll on a table — with possibilities for both good and bad effects, depending on the roll. [Maybe something like this?]
- At least one item of treasure that is cursed or has other detrimental side-effects on the owner/possessor.
- Some sort of “false climax” where inattentive players will think they’ve won the adventure and either let their guard down or go home, while clever players will realize this couldn’t have really been the climax. [Also, there can be a well hidden chance to end the dungeon earlier, even from the beginning. I used it here and my group discovered how to do it but refused to. It has to do with a sacrifice and an eye.]
- At least one disorienting effect, teleporter, mirror trap, [swiveling] floor, or maze like monster, up is down too.
- An area where resources are an issue. Wet torches or wind blowing them out. Oxygen low or having to hold your breath to swim [through] a tunnel.
- An area that has items of value, but they are too large to transport, or cause someone to have his hands full at an ambush.
- A creature that appears to be something it is not. Some examples: Lurker above, mimic, [cloaker], wolf in sheep’s clothing, doppelganger, gas spore (perhaps my favorite), etc.
- One encounter (no more, no less) that makes absolutely no logical sense, that the DM completely leaves up to the players’ imagination to explain. [Always a favourite of mine, specially ultra-futuristic science or weird, outer technology.]
One doesn’t have to include all 12 in every dungeon, but consider that each element adds to the final result, and in big dungeons, the more the better (otherwise it can end up repetitive or boring soon.)
Some of these elements can be combined, like a creature that appears to be something it is not and a trick/obstacle for the players to think through it. In the case of Slime Bugs, these two elements inspired me to create the infamous “petrified cube”, or the gasslime trick/trap I included on The Goddess of the Crypt.
Some additions I want to include in (all?) my future dungeons and adventures:
- Lots of things to interact with. You know, levers, buttons, ray guns that cause random effects.
- Replacement adventurers. Prisoners or lost adventurers than can join in in case a PC dies. I made this supplement for Into the Odd.
- Things (traps, tricks, monsters, spells, npcs) that break the rules. You know, monsters that hits automatically, peasants than cast spells without following magic-user or cleric rules, anything.
- Things than don’t do a thing but look intriguing and make PCs waste time, triggering random encounters.
- Rooms outside time and space or, at least, outside the main dungeon.