No problem. Here’s how to build a simple, effective dungeon in under 5 minutes.
Grab a piece of paper, and draw a small box at the top of the page, just large enough to fit about 10 words.
You’re going to build a 3-room dungeon, where each room simply connects to the next in a line.
Next, draw three large boxes on your piece of paper, filling most of it. Label the boxes “1,” “2,” and “3,” and connect them with lines (see the bottom of this post for an example).
Choose the type of environment or roll for it. Write this down in the small box at the top of the page.
|1||Classic underground dungeon|
Choose two types of monsters: the main threat of the adventure, and another monster type that either helps the main monsters or are natural denizens of the environment. Write these down in the small box at the top of the page.
Invent something that the main monsters took that the PCs need to retrieve: a magic item, a victim from a nearby town, an important ritual component, etc. We’ll call this the Maguffin. Write this down in the small box at the top of the page.
Room 1: Introduction
This is a foyer/entrance to the environment. This will contain half as many main monsters as PCs. Write this down in the box labeled “1” (e.g., “2 goblins”).
Treat this as a basic fight, and use it to describe the dungeon and the main monsters, orienting the players to the kinds of fights they should expect.
Room 2: Complication
This room contains a trap or other obstacle, and optionally contains supplemental monsters (as many as seem reasonable).
|1||A statue fires an arrow at a random target every turn; moving two levers on the statue deactivates it|
|2||Stepping on certain floor tiles causes darts to fire at the triggering creature|
|3||Stepping on certain floor tiles triggers a pit/spike trap|
|4||The greased floor causes PCs to slip in random directions|
|5||As soon as the PCs enter the room, doors close and water begins pouring in. Levers at the other end of the room must be pulled in a specific order to drain the water.|
|6||Magical runes have been inscribed on the floor, granting bonuses (such as +2 AC) to the denizens of the dungeon if they stand on them, but penalties (such as -2 on attacks) to intruders.|
|7||A pool in the center of the room contains money or a valuable object. However, the pool itself is a monster (like a water elemental or an ooze), or the pool is actually acid.|
|8||A tripwire causes cleverly concealed boulders or tiles in the ceiling to fall on those entering.|
Write this description in the box labeled “2,” as well as the supplemental monsters (e.g., “Dart trap, 2 stirges”).
Room 3: The Face-Off
This room contains a large force of both monster types, about 50% more total monsters as PCs, as well as the Maguffin. In the box labeled “3,” write down the monster mix and the Maguffin (e.g., “4 goblins, 2 wolves, Wand of Fireballs”).
Put the Maguffin in danger at the other side of the room. Some of the monsters are about to use the magic item, kill the victim, burn the ritual component, etc. Make it clear that they will do this in a few turns unless the PCs stop them, but they’ll have to get through other monsters to do so.
If possible, introduce an environmental effect here: a multi-level room, lots of cover, a lava flow, or something else to spice up the fight.