Since pulling the plug on Evolve, indie developer Turtle Rock Studios has apparently moved over a new project in collaboration with free-to-play online game publisher Perfect World. What is it? Dunno exactly, but according to an interview over on GamesIndustry with company co-founder Phil Robb, it’s “a new franchise set in an all new universe that leverages the style of gameplay our community loves” and features “heart-pounding moment-to-moment online co-op FPS action”.

Turtle Rock also developed the cult-popular Left 4 Dead, and assisted with the production of several Counter-Strike games.

“What we can say is that we are definitely going back to our moment-to-moment gameplay roots with a huge focus on co-op FPS,” adds studio boss Steve Goldstein. “There will be plenty of baddies to shoot up, but it is not a ‘zombie game’ or anything post-apocalyptic. What we can say right now is there’s a strong dark fantasy element to it.”

Whatever it is, though, it’s being built with Unreal Engine and won’t be out until 2018.