I am looking for a game which has co-op mod.Can someone help?

Hi everybody i m looking for a game which has co-op mode.Such as modern warfare 2 or splinter cell. İt can be in every game genre. My system can play modern warfare 2(low quality) Any suggestions?

HL2 has a s***load of mods, quite a few of them being co-op, plus HL2 itself is pretty awesome. And if you can run MW2, you can definetely play HL2 on high settings. Try these mods: Obsidian Conflict, Synergy, Zombie Master, and Zombie Panic! Source.

Left 4 Dead 2 Whats your Steam thing? I'll add you. biggest_loser

Left 4 Dead 2, Resident Evil 5...