Despite being a beloved zombie shooter series, we've not heard from Left 4 Dead in years, but Techland has given us something to shout about, as they've tweeted about a mysterious collaboration between Dying Light and Left 4 Dead 2, along with the picture below.
We're promised some "serious zombie slaying" in the style of Left 4 Dead, but that's all the information we have for now. With Left 4 Dead 2's 10-year anniversary coming next month though, we may well see something happen then.
What could it be?