Counter-Strike 1.6 is a modification of Half-Life that managed to achieve greater success than Half-Life itself.
Its gameplay is what draws most attention, coming very close to reality (for the time of release, of course!).
Certainly CS 1.6 is one of the most famous first person shooters in the world (until nowdays).
Here you have to choose a side (terrorists or counter-terrorists) and go into combat, gunfire, grenades and lots of blood is what you will find!