Turtle Rock Studios has announced that over 10 million players have played Back 4 Blood since its release last fall.
News of the milestone comes alongside the announcement of the first DLC, Tunnels of Terror, which will be made available on April 12.
The content will be releasesd as part of the Back 4 Blood: Ultimate Edition, Back 4 Blood: Deluxe Edition, Back 4 Blood Annual Pass, or via standalone purchase. The expansion will feature the new Ridden Hives PvE cooperative activity, new playable Cleaners and Ridden variants, exclusive character and weapon skins, and more.
"To achieve such a milestone in the short time since the release of Back 4 Blood is a historic event for our studio and this franchise," said Turtle Rock Studios president and general manager, Steve Goldstein.
"As we look ahead, we’re excited to keep the momentum going with our upcoming expansion, Tunnels of Terror, which will offer more cooperative content for fans to continue cleansing the world of the Ridden."
In Tunnels of Terror, teams of up to four can participate in a new co-op activity known as Ridden Hives. Here, they will explore seven different dungeons full of tunnels below the depths of Evansburgh where a new type of Ridden reside called the Warped Ridden.
To claim exclusive loot and rewards only offered in Ridden Hives, players must outmaneuver and overcome the new Warped Ridden, including the landmine-setting Urchins, Shredders, and damage-dealing Rippers. The new Warped Ridden variants are also playable in PvP Swarm mode.
The upcoming expansion will introduce two new playable Cleaners – Sharice, an axe wielding firefighter, and Heng, a restaurateur. Also included in Tunnels of Terror are eight exclusive character skins, seven new legendary weapons, 12 new weapon skins, new cards, and more.
The expansion will coincide with the release of the No Hope difficulty setting, a free update adding an extra level of challenge for elite players. It's worth noting that all playable content included in the Tunnels of Terror expansion will be accessible by all players in a party as long as one player in that party has purchased the expansion.
Additionally, there will be no microtransactions of any kind, cosmetic or otherwise, added to the game as part of this expansion or any future content update.
Back 4 Blood is a first-person co-op zombie shooter from the creators of the Left 4 Dead franchise and is available Xbox Series X/S, Xbox One, PS5, PS4, and PC.