Released: 2003
Developer/Publisher: Valve for Microsoft Game Studios
Platform(s): XBOX, PC

It was originally a Half-Life mod, but Valve went ahead and officialized this tactical FPS for general commercial release—and that was all she wrote. Not only is it still played six years after release, but it boasts one of the most insanely dedicated user communities of all time. Blucka blucka!

YOU AUGHTA KNOW:
Police officers in the Chinese city of Tianjin played CS as part of their anti-terrorist training.