This is not earth-shattering or anything, but you can easily run the game Doom under Knoppix. You need two packages:

prboom_2.2.2-1_i386.deb
doom-wad-shareware_1.9-1_all.deb

Convert these to tgz files:

alien --to-tgz prb<tab>
alien --to-tgz doo<tab>

Don't worry about the "permissions" errors. Extract the files from the tgz's, then move the .wad files into the same folder as the prboom executable. Then run prboom in a terminal. Fun!