2D

Left 4k Dead [2D Left 4 Dead]

I don't know if you heard about this, but it deserved to be posted.
This little java game is made of pure win!
Not only it's fun and challenging to play, but it also weights only 4 KB!

Congrats to Markus Persson for the awesome game and the programming skills.

A little tip if you are experiencing issues: update your Java Runtime Enviroment!