Counter-Strike (or CStrike, or CS) is another great mod for Half-Life. Orignially created unofficially by a group of "average mod makers", Counter-Strike's success is shown by Valve (makers of Half-Life and TFC) who have made the mod official, and are helping to release thae next version of CS, v1.0. This will be included in the next Half-Life patch.
Counter-Strike is another team based game, with Terrorists against Counter-Terrorists.You start the game with a pistol and a knife, and some money (points, in effect). This money can be spent on weapons (out of about... 22 odd i think. I ain't sure though, so check out the CS homepage if i've added it yet), armour, ammo and other useful things. You gain money/points by completing mission objectives or killing enemies.
The game is played in a very realistic way, when you die, you die and have to sit out the round. Oh yeah, the game is played in 'rounds', of about 5 minutes each. In this time you have to win the round, by capturing hostages or killing all enemies. Some maps feature different scenarios, check the hompage for more information about these.
My clan, [UKE] (UK Elite) also plays CS, but currently has very few members.
Visit these links to find out more about CS:
Official CS page