Valve publishes source code of Left 4 Dead prototype in Counter-Strike update

Valve has published the source code for Terror Strike, an early Left 4 Dead prototype. The publication was probably accidental and happened via an update of the first Counter-Strike game. A mod has now been released to play the prototype.

It is a gameplay prototype with its own folder: zombie_city. The game mode uses a lot of Counter-Strike assets, such as weapons and the characters. The terrorists have to plant a bomb in an urban environment, while counter-terrorist zombies appear here and there and the player tries to counter them with knives. The player must shoot these zombies, after which they respawn. Once the player plants the bomb, more zombies will appear. The One Epicplayer: Blue Shift shows on YouTube how the game mode works and also explains how players can try out the mode.

The source code appeared last week in an update for Counter-Strike, in honor of Valve’s 25th anniversary. It is not the first time that parts of Terror Strike have been leaked: this also happened earlier this year. The zombie_city map was created based on that leak. That mod is for Counter-Strike: Source and the new mod is for Counter-Strike: Condition Zero. Left 4 Dead was made by Turtle Rock Studios.