VIDEOS:
Glorious L4D2 mods
Left 4 Dead 2 has Steam Workshop integration, which allows users to upload game modifications for anyone to download. From changing survivors' appearances to other characters, making the common infected teletubbies, making everyone bleed Danganronpa blood, and making the Hunter sound like Charlie Kelly from Always Sunny, one can make the game barely the same anymore.
Example of:
Game Mod
Example of:
Climactic Elevator Ride