"Valve Software's newest game, Left 4 Dead, is a first person zombie shooter with Valve's typical high polish and refinement. But how does it perform? We'll show you, on the latest video cards from AMD and NVIDIA with plenty of image quality screenshots to boot.

... One of the foremost features of Left 4 Dead is the online co-operative campaign. Players can team up with three of their friends, or even complete strangers, to play through each of the game's four Films. There is also a “versus” mode, adding the ability to play as the infected against survivor adversaries. Left 4 Dead makes extensive use of Steam's achievement system throughout the single-player campaign, and all multi-player modes. Teamwork is a key part of Left 4 Dead's gameplay, and the survivors must protect each other along the way. Players are recognized for protecting each other, healing each other, and for giving each other a hand up when they are knocked down.

...  Left 4 Dead runs on Valve's venerable Source engine, which also powers other Valve games such as Half-Life 2, Counter-Strike: Source, and Portal, among others. Source is a DX9 engine, and does not currently support DX10. Thus, Left 4 Dead is a DX9 only game. Of course, it will run on Windows Vista systems equipped with DX10, but it will not make use of DX10's features. Source is a massively powerful and complex software package. Interested parties can look at Valve's Source Brochure (link to PDF) for more information on the engine."