Shooter
Shooter games are a sub-genre of action games, which often test the player's speed and reaction time. It includes many subgenres that have the commonality of focusing "on the actions of the avatar using some sort of weapon. Usually this weapon is a gun, or some other long-range weapon. Read the full article at the Wikipedia.
It came from space, and ate our brains
Your name is Jerry, you’re a bald, no-nonsense kind of guy equipped with a flashlight and you know how to handle a gun.
Genre: Shooter, Action 
Signal Ops
Steam (19 Nov 2013)In Signal Ops, you guide agents from the relative safety of a control room.
Genre: Shooter, Stealth, Action 
Ace of Spades
OpenSpadesAce of Spades is a creative online multiplayer FPS that gives the player complete strategic freedom over a constantly evolving sandbox.
Genre: Shooter, Action 
3079
v2.19 (6 Nov 2013)3079 is a futuristic, open-world action first-person role playing game.
Genre: Shooter, Role-playing, Action 
Fields of War
Release (9 Nov 2013)Fields of War is a massive multiplayer third-person mech shooter focused on large scale battles, territory control, skill and most...
Genre: Shooter, Action 
Half-Life: Opposing Force
by Gearbox
(6 Jul 2013)
Return to the Black Mesa Research Facility as one of the military specialists assigned to eliminate Gordon Freeman.
Genre: Shooter, Action 
Metro: Last Light
by 4A Games
Steam only
(4 Nov 2013)
It is the year 2034.
Beneath theruins of post-apocalyptic Moscow, in the tunnels of the Metro, the remnants ofmankind are besieged...
Genre: Shooter, Action 
No More Room in Hell
Steam Only (31 Oct 2013)When there's no more room in hell, the dead will walk the earth.
Genre: Shooter, Total conversion, Action 
Painkiller: Hell and Damnation
by The Farm 51
Beta - Steam only
Heaven's Hitman is Back... With a Vengeance
Evil has returned! Demonic powers are manifesting themselves as a myriad of dark creatures,...
Genre: Shooter, Action 
Monaco
Linux port (21 Oct 2013)Monaco: What's Yours Is Mine is a single player or co-op heist game.
Genre: Shooter, Stealth, Strategy, Action 
Dark Matter
by InterWave
Release
(17 Oct 2013)
Dark Matter is a 2.5D side-scrolling survival horror game, set in a derelict spaceship besieged by a sinister alien presence, and infested...
Genre: Shooter, Role-playing