Well if you still want some kind of reward scheme. I suggest making it small. maybe have locked rooms with better weapons and ammo and what not. Just plan out ahead of time what rooms carry what items. When a player reaches via room, tell them what they recieved.

Won't there have to be a dungeon master too?

Oh and for perks look @ fallout for inspiration, like as you level up you can get better perks

Yep. I could have some unlockable perks and some other ways to mix things up.
Dungeon Master? Why that would be... ME!

Edit: The Creeper 2010 is now up and running! If you like the idea please join!

So is that it? Do we have anything else we need to consider?