Abyssus is a "brinepunk FPS" (whatever that means) from DoubleMoose Games, The Arcade Crew, and Dotemu. After arriving on Steam last year, it has received a handful of major updates. The latest update, version 1.3, does not seem to be popular with Steam players. On the plus side, Abyssus also just launched on Xbox Series and PlayStation 5, and those players probably won't be attached to a previous update. There is 4-player online co-op with crossplay and plenty of brine in store for them!