Left 4 Dead
Version and / or Patch Used: Latest Steam Update
Timedemo or Level Used: Custom Timedemo
Developer Homepage: http://www.valvesoftware.com/
Product Homepage: http://www.l4d.com/
Left 4 Dead uses the latest version of Valve's Source engine, with improvements such as multi-core processor support and physics-based animation to more realistically portray hair and clothing, and to improve physics interaction with enemies when shot or shoved in different body parts. Animation was also improved to allow characters to lean realistically when moving in curved paths.
Rendering and artificial intelligence were scaled up to allow for greater number of enemies who can navigate the world in better ways, such as climbing, jumping or breaking obstacles. Lighting has been enhanced with new self-shadowing normal mapping and advanced shadow rendering that is important to convey information about the environment and player actions.
HD 4850: We see a FPS drop or two across the board.
HD 4870: Performance has taken a dip at all resolutions.
HD 4870 X2: The HD 4870 X2 sees a pretty big drop at the lower resolutions, but it's still very playable.