Some of the tweaks and fixes includes as follows:

– Darkened the Lighthouse background movie and increased the contrast with the user interface elements
– Chapter selection is now available when creating a Survival lobby
– Single player coop now works correctly after playing Survival online
– The correct game mode will be set when playing back a demo
– Changed holdout server spew to be development only
– Stats are no longer updated while viewing a demo
– Correctly update the leaderboard based on the player’s personal time, not the team best time
– Show the player’s best time in the scoreboard
– Removed Survival exploits from The Terminal, Last Stand, The Crane, The Boathouse and The Warehouse
– Fixed tanks sometimes not spawning after 15-20 minutes

Left 4 Dead was developed by Turtle Rock Studios, now owned by Valve. The game uses the Source engine and  was released for PC and Xbox 360 in November 2008.