Synergy provides some of the most fun you can possibly have online; If you think the concept of playing Half-Life 2 with your friends in co-op sounds exciting, then don't hesitate and download this quirky, entertaining, hystericaly glitchy gem!

The best super-hero game of all time; play it. Now.

Quite possibly one of the finest source-based mods ever made -- teaming up with a coordinated squad of intrepid, human survivors is pure bliss and the game is fantastic at generating tension with its moody, bleak atmosphere and the objective-based structure works terrific here. A must download for every Steam user.