I ran the finale of a campaign involving the Labyrinth of Baphomet, which had a ground of piled bones and walls of mortared elephant tusks, over which a sky of stormclouds red in the sunset drizzled blood. There was a time limit because the labyrinth was slowly flooding with blood.
In truth they weren't physically in the labyrinth, but had been caught in a psychic attack that trapped their minds in a projection of the labyrinth, and if they could not escape in time their minds would be destroyed, leaving them as feral beasts.
The actual map was fairly simple (I can't find exactly what I used, but it was something like this:
http://www.astrolog.org/labyrnth/art/3start.gif), but it had lots of circles so mapping it would be an incredible challenge, and they didn't have time anyway. Also, the entire village they were protecting has its inhabitants scattered around the maze, so the party has to decide how long they can spare rescuing people and how fast they want to look for the exit.
Oh, and there are demonic minotaurs, and a few townsfolk who've gone mad.
And whenever the PCs kill anyone, the walls shift, eliminating some options for how to escape.
After a few minutes the blood is deep enough to slow them down. Eventually it's too deep and they have to use the corpse of a giant monster (one they'd killed earlier in the campaign) as a raft. So they're
whiteredwater rafting through a labyrinth. And as they near the exit an aspect of Baphomet tries to bar their way, leaping between the walls, attacking them with his infernal spear. It only takes one PC getting out of the labyrinth in order to stop the Bad Thing that's driving everyone mad, but most PCs were blood-thirsty and tried to kill the boss, which nearly got them killed.
It was a cool scenario, where the labyrinth was backdrop, and precise navigation wasn't important.