Left 4 Dead 2
From PCGamingWiki, the wiki about fixing PC games
Left 4 Dead 2 is a cooperative first-person shooter video game. It is the sequel to Valve Corporation's award-winning Left 4 Dead. The game launched on November 17, 2009, for Microsoft Windows and Xbox 360 in the United States and November 20 in Europe; in 2010, Left 4 Dead 2 was made available to the Steam client for Mac OS X. It builds upon the cooperatively-focused gameplay of the original and uses Valve's proprietary Source engine, the same game engine used in Left 4 Dead. The game made its world premiere at E3 2009 with a trailer during the Microsoft press event.
Console Commands
Games running on the source engine can utilize Source Engine Console Commands for various tasks.