brainstorming noncombat encounters for my mega dungeon

[Varyon]

I can't recall all of the specifics, but in D&D I once had a large, ornate door with multiple keyholes. Once you started fiddling with one, it activated a mechanism that, if the door wasn't opened within a set period of time, would seal off the unlocking mechanism for several days. To get the door open, normally one would use multiple keys, turning (and leaving) them in each lock in a specific order to fully unlock the door. To pick the locks, you need to pick them in the right order, and leave a pick (with someone holding it, or using some other method to prevent it from moving; the keys were shaped just right to lock in place), which results in penalties as you keep working, as your kit is slowly depleted. It was designed for a new mechanic of D&D 4e, longer-term activities where every character could attempt to influence things (I had a variety of skills usable, fluff-wise for things like identifying the order to unlock it in, tricks to make unlocking easier, methods of improvising picks to hold the lock open to prevent penalties, etc, but mechanically it was pretty much just "get n successes within the allotted time"), but would work just fine for GURPS as well.

In that, the reward was a secret room that had some pretty solid treasure as well as a special scroll that would wipe out all the undead spread throughout the dungeon (making things a lot easier on the characters). It also contained a backdoor that allowed them to sneak into the dungeon right by the animal pens and barracks, allowing them to stealthily take out the few kobolds at the barracks, avoid needing to fight the giant rats still in their pens, and even let them kill a large number of the kobolds in their sleep by getting into the barracks. Or, at least, it would have if they didn't decide to kill the rats in their pens, making an ungodly racket and waking up the sleeping kobolds.


A teleportation room is also useful. You could even have multiple ones spread throughout the dungeon, with specific codes to reach each - this can allow characters to more readily pick up where they left off earlier.


An apparent pit trap that has some useful/valuable (if perhaps dangerous in some way) gunk at the bottom can be interesting, as the characters have to figure out a way to reach and harvest it safely. In the same dungeon as the special door, I had pits of glowing green stuff, which the players assumed was acid up until they knocked a kobold in. It was actually a glue-like substance (the same stuff the kobolds used in their glue shots, which were basically sling pellets that also had a tanglefoot bag effect). They ended up not trying to weaponize it themselves, sadly.