I just want to promote a small Arena Shooter, I played today at the Game City in Vienna. The game is called Shiro 011 and is developed by 2 guys. Even though they just started the developing process a few months ago the core game (currently it's pretty much just the core) feels better then a lot of early access games released on steam.
You can download the Alpha build for free at http://www.indiedb.com/games/shiro-011
A few facts:
A somehow unique feature of the game: You have to aim/ironsight to be able to shoot.
Game-Mode: FFA or Team Last Man Standing
Instagib
Bullet Time
The game uses the Unreal Engine 4
It can be played online and over an LAN connection.
There may or may not be a text to speech lobby.
As it is currently multiplayer only, you have to play with friends, otherwise it is pretty unlikely to find an open server.
There are plans that there will be a single player modus aswell, were you go through a level shooting enemies and dodging enemy bullets.