Counter-Strike: Source

Counter-Strike: Source (CS:S) is the latest incarnation of Counter-Strike. As the name implies, the game is a modification of Valve Software's Source engine instead of the Half-Life engine (which in turn was largely based on the Quake and Quake II engines.)

As of August, 2004, the only legal way to play CS:S is by visiting an Internet cafe participating in Valve's Internet cafe program, or by buying Counter-Strike Condition: Zero, which entitles users to download the game using Valve's Steam software.

Some features new to CS:S include very improved physics and three-dimensional skyboxes, along with better graphics and other small tweaks (such as players dropping grenades when they die).