A recent blog post entitled "Follow up to functional programming doesn't work" recently caused a bit of a stir, encouraging Haskell programmers to dredge up the nearest things Haskell has to real computer games. A Super Mario clone, Frag (a reimplementation of part of Quake), a Gradius clone, 4Blocks and a game that blows all of the others away called Bloxors:
This beautiful little OpenGL-based puzzle game weighs in at just 613 lines of purely functional code (many of the other games use unsafe* functions to introduce uncontrolled side effects). This is also one of the few programs that cabal install actually works on.
Check it out here!