Games have come a long way. Ten years ago people would be shocked by how good games like Left 4 Dead look. But how about twenty years ago?
If Left 4 Dead came out in '88, maybe it would look something like Left 4k Dead. Left 4k Dead was made by a guy named Markus Persson in Java, for the 2009 Java 4k Competition. That "4k" means that all entries to the competition must be under 4 kilobytes only -- which is less the size then many README files for games.
The game is pretty simple and fun. You know the drill: shoot zombies, try to survive. The level creation is random but you don't have any teammates here -- it is just you and your guns against the undead masses.