Anyone who's played hundreds of hours of the Left 4 Dead games may have nothing left for them in terms of vanilla content. To that end, Valve has opened up the floodgates to allow modders to create their own original content for the game, all of which is freely shared over the Steamworks database on Steam.
That being said, much of the content players still enjoy and experience is the vanilla content. With the vanilla content in mind, Valve has released a new patch that updates both Windows and Linux versions of the game with fixes for some previously existing exploits and bug fixes for the game's many maps.
Here are the patch notes in full, via PCGamesN.
Windows
Changes:
Updated some mutations to remove instances of invalid weapons or enemies
Fixed Cold Stream image in Campaign select menu
Fixed possible insta-kill when shoving a jockey who is mid-leap
c11m2
Restore freezer door in co-op mode
Restore crane lowering sound
c9m2
Break some barricaded doors so survivors can reach supplies
Restore missing fire particle system
Restore color correction for both Crash Course maps
c8m1
Fixed survivors facing the wrong direction after intro
Restore alarm clock in downstairs bedroom for co-op mode
c8m4
Restore missing rain particle systems
c8m5
Restore some missing chopper pilot lines
Move survivors out of view during the escape sequence
Linux
General
Fixed possible insta-kill when shoving a jockey who is mid-leap
Fixed Cold Stream image in Campaign select menu
Remove ammo piles in Gib Fest Mutation
EMS
ent.GetEntityIndex()
ent.EyePosition()
ent.GiveItem( itemname ) – Give an item/weapon by name. ("health", "katana", "rifle_ak47", etc.)
ent.GetButtonMask() – returns a bitfield of currently pressed buttons. Recognized buttons are: IN_ATTACK, IN_ATTACK2, IN_JUMP, IN_DUCK, IN_FORWARD, IN_BACK, IN_USE, IN_MOVELEFT, IN_MOVERIGHT, IN_RELOAD