Updates to Left 4 Dead 2 have been released. The updates will be applied automatically when your Steam client is restarted. The major changes include:

Left 4 Dead 2
  • New Community Mutation: Riding My Survivor
  • Added support for raw mouse input on PC. Raw input reads directly from the mouse, bypassing Windows control panel mouse settings. This addresses issues with high DPI mice, and provides for a more reliable controller experience at various resolutions
  • Improved Support for mouse acceleration, for use with raw mouse input
  • Fixes for stability issues on some Intel chips
  • Various rendering fixes for Mac