Left 4k Dead is a Java based game created byMarkus Persson, of king.com.  Markus created this game as a entry to the 2009 Java 4k Competition where the entire game itself is less than 4k. 

Playing this game was addicting and was less scary compared to the actual left 4 dead (obviously since its just pixels ><). I couldn't finish the game it self because i keep getting lost. but this is a good time killer and the most amazing part to me is that, as a programmer myself, is that the code for this game is short and quite simple.

via Mojang