Valve accidentally leaks Left 4 Dead prototype in Counter-Strike patch

^{Image: Valve}

It looks like Left 4 Dead started out as a Counter-Strike: Condition Zero mod, and you can now try it yourself. 

Counter-Strike 1.6’s latest update inadvertently included Valve’s earliest prototype of Left 4 Dead, back when the zombie game was a simple mod called ‘Terror Strike’. The mod was leaked online along with a bunch of old Counter-Strike maps, all of which are fully playable providing that you’re able to get your own server going. 

Here’s what the Left 4 Dead prototype looks like in gameplay:

Wait, Left 4 Dead was a Counter-Strike mod all along?

According to dataminer Tyler McVicker, this Left 4 Dead prototype started out as a mod for Counter-Strike: Condition Zero. A description of the mode was provided by X/Twitter user Gabe Follower:

The terrorist with the bomb must make it to the house and plant the bomb. Zombies will respawn a little bit after being killed. Once the bomb is planted, every zombie will respawn and a horde will come for the survivors. The survivors must survive the horde by killing all the zombies. The round is won when all zombies are killed while the bomb is planted.

In this mode, players would play as terrorists fighting back hordes of counter-terrorists while trying to plant a bomb. The terrorists would be equipped with guns, while the counter-terrorists would only use melee attacks - so you can see where the core Left 4 Dead concept came from. In case you’re having doubts however, Left 4 Dead’s director Mike Booth confirmed the mod’s origins on X/Twitter one year ago:

Booth and his team at Turtle Rock, formerly known as Valve South, were primarily responsible for working on the mod before it gained proper traction at the company. Once the mod gained a champion in ex-Valve writer Chet Faliszek, company head Gabe Newell approved moving it into full development as an actual fleshed-out co-op survival game. The game was eventually published in 2008, and the rest is history. 

This Terror Strike mod was reportedly ‘accidentally compiled’ by Valve and pushed out in a recent Counter-Strike update, but the files were almost immediately taken down in the following update. That didn’t stop leakers and dataminers from getting their hands on the mod and putting it all online for everyone to try out, of course. 

We’re not sure if you could try playing Terror Strike on your brand-new Steam Deck OLED, but it’s worth a shot. You can find the mod here.