Ballistic Overkill, the really fun and dirt cheap online FPS is now available in more countries! On top of that, they worked on some more optimization.
No More Room in Hell 2 is not just a sequel, it's going to be running on an entirely different game engine. The developer have said will be doing a Linux version, but their wording has been iffy.
Interstellar Marines was once an incredibly promising FPS game with nice visuals and interesting gameplay. Sadly, their money pretty much vanished, but it's pleasing to see it still being developed.
Counter-Strike: Global Offensive, the popular FPS from Valve has another update with one rather interesting feature. You can now join game lobbies made by members of Steam groups you belong to.
Personally, I am interested in playing Homefront: The Revolution even if it's not the best FPS ever made. The good news is that it looks like the Linux port is still being worked on.
Killing Room is an FPS from Alda Games was supposed to be on Linux day-1. It was delayed due to issues with the Linux version and getting the Windows version ready, but now it's even less certain.
A simple game at heart, but an incredibly intense game thanks to the deeply evil atmosphere. Devil Daggers is an FPS where your only aim is to survive for as long as you can and beat not only your own previous score, but everyone else's at the same time.
Natural Selection 2 is the RTS/FPS hybrid that's pretty damn fun and it has just been updated. You can now get a new game-mode from the Steam Workshop and the entire game is free to try all weekend.
Good news for Arma 3 fans today, as Bohemia Interactive have released their next roadmap. They have stated work is going to continue on the Linux version! Not only that, but they are going to make Arma 3 64bit too.
'Polygod' is an Early Access FPS with a focus on random generation and high difficulty, the developers just released a Linux version and need feedback.