It's been a long time since we've heard anything about Back 4 Blood, but thankfully it looks like the Left 4 Dead spiritual successor hasn't returned to the grave. Developer Turtle Rock Studios (who was acquired by, then separated from Valve during Left 4 Dead's development), still isn't giving much away about Back 4 Blood, but you can now stare at a single piece of concept art.
Back 4 Blood was announced back in March 2019, and in the time since we've learned very little. It's a co-op FPS where you put zombies back in the ground, with PvP, a campaign and a new universe—so it's not officially connected to L4D. And that's about it. The concept art, however, does give us a few clues about what to expect.
A fort suggests that it's been some time since the zombies first appeared. It's a makeshift deal, covered in barbed wire and rusty, corrugated iron, but it's big and pretty elaborate—too elaborate for this to be early on in the zombie apocalypse. And given that Turtle Rock has chosen to show this off first, it probably has a lot of significance. Perhaps it's a hub where the party can prepare between missions, like Vermintide 2's Taal's Horn Keep.
The Left 4 Dead series is all about escape, with the party trying to find a safe haven right after the virus starts turning everyone into ravenous corpses, but the concept art and even the title itself, Back 4 Blood, make me think this time it's going to be about fighting back. Maybe we'll be patrolling, clearing areas and chipping away at the horde instead of constantly running to evacuation points.
At this point, however, it's all speculation. We've not even seen a screenshot yet. And as for a trailer? "We're working on it," says Turtle Rock, more recently known as the studio behind Evolve.