RPGs have dungeons...well more often those dungeons are caves...no, actually RPG plots often feature caves, which we call 'dungeons'. Anyway, these caves look rather strange, because people began drawing them on graph paper, and later they made sure to fit the entire map onto a single square at the top of a page.
RPG caves look very strange, yet disappointingly bland. But I've been thinking...
Depths and Turns
Caverns could present the same kinds of challenges as wilderness survival, but very different in the details.
You enter the cave's mouth. Heavy imprints of the umber hulk have textured the mud, making it easy to follow.
An hour down the passageway, you find a fork in the tunnel, one going down, the other off to the side. The passage stopped being muddy some time ago, and the bare rock gives no hints about where the umber hulk might have gone.
What do you do?
How about some natural fireballs? The worst thing about pockets of natural gas is that you can't light a torch in them, so you must enter blind.
Why would the smaller creatures, like goblins or gnomes, build big tunnels, wide enough for a person?
A sudden spear launches from a shadow in the wall. Looking closer, you spot a small tunnel, just large enough for a man to squeeze through...
Even worse than a tunnel too small to fit through is one just large enough to fit through, with enemies waiting on the other side.
I once spoke with someone who goes spelunking. He mentioned the dangers of old bridges.
- Stage 1 is a standard wooden bridge, built to cover a dangerous gap.
- Stage 2 is when so much debris covers the bridge that it looks like a natural part of the cavern - just another part of a tunnel.
- Stage 3 is when it goes rotten.
Of course, the bridge will not collapse, even when rotting, until something puts its weight on top.
Caves have limited oxygen. The open flame of a torch will limit the oxygen even more. Eventually, people get confused and start the giggle, then hallucinate.
I don't know how to best represent 'confusion' in a game, but perhaps something like a time-skip, where the GM informs players their characters were discussing something while resting, then became confused about the topic, and went through three torches. They think it might have been a long time and feel hungry. Then the GM sets an egg timer for 1 minute...
Caves can flood.
The umber hulk backs away, jumping into a puddle. The massive splash suggests the puddle covers a tunnel somewhere.
How do you proceed when the way is blocked by water? Of course you can enter, but you'll have to enter blind, and cold.
And what if the passage branches underwater?
You jump in, bracing yourself against the freezing, stagnant waters. Pushing forward, you find the tunnel takes a turn left; but as you feel around, you find the tunnel goes forward too. Which passageway do you take? Forwards or left?
Things could be even worse. Goblins, using the cavern as their base of operations, could live behind a maze of water. Each passage leads nowhere but through tunnels full of freezing water.
It's the perfect trap...