Chex Quest!!!
Thats right Chex Quest, for those of you who don't know (I feel bad for you) this is a game that came in some boxes of Chex Cerial way back in the day. We'll I was on Digg today and saw that the game is now open to the public, free of charge! Check it out here. The game runs in DOS and has graphics akin to the original Doom.

Download site.