Another free weekend event has kicked off on Steam, and this time it features the still-in-development Killing Floor 2.

The cooperative zombie shooter is currently free to download and play as much as you want on PC until Sunday, September 6, at 10 AM PDT.

This is the full version of the game as it currently exists in early access, and includes all of the content released as part of a major free update earlier this week. It added two new perks (the game’s parlance for classes), the Firebug and Demolitions; new weapons and grenades for each of those perks; two new maps; an overhauled skill tree for the Berserker; new achievements; support for Nvidia’s PhysX Flex tech; and more.

Alongside this update, new crossover promotions were introduced. If you own Chivalry on Steam, you’ll now have access to a playable Knight character and the Zweihander sword. If you own Red Orchestra 2, Anton Strasser is now available as a playable character.

Coinciding with the free weekend event, the game is 33 percent off, bringing its price down from $30 to $20. There’s also a six-pack on sale for $100, bringing the price of each copy down to under $17. These prices are available until Monday, September 7, at 10 AM PDT.

Killing Floor 2 remains in early access. If you’ve been unsure about dropping money on the game before its full release, this is an ideal opportunity to give it a spin.