Skipping over some well known ones for lessor well known ones (ok, some well known ones as well). Also included some 3rd person shooters
Call of Duty: World at War. 1st semi modern looking COD, Ok campaign.
Doom (2016). Old School Gaming..who needs regenerating health?
Doom 3. Old School. Better with mods like Absolute HD
Quake 4. Old School. Need to edit a file for WS, but was good shooter.
Legendary. Fight against classic monsters (werewolves, etc). Can be found Super cheap on sale sometimes (like less than a dollar)
Aliens vs Predator (2010). Short campaigns as the iconic Alien, Predator, or Colonial Marine
Borderlands 1 & 2.
Bioshock.
Bioshock Infinite.
Bulletstorm. Go for over-the-top ways of killing the enemy using your weapons AND the things in the environment.
Call of Juarez: Bound in Blood.
Call of Juarez: Gunslinger.
Crysis. . Special forces with super-suit powers that isn't quite open world, but gives you BROAD ways of approaching your objectives
Crysis Warhead.
Crysis 3.
The Darkness II . Use guns or your supernatural dark powers for vengance
Dead Space
Deus Ex
Deus Ex Human Revolution
Dishonored
F.E.A.R. . Supernatural horror shooter with bullettime and decently smart AI. Starts slow, but gets rolling.
FarCry 3 . Open world, shooter
FarCry 4 . Open world, shooter. Those D&*N eagles!
FarCry: Blood Dragon. . Lambasts shooters and 80's-90's action movies.
Half Life 2: Look for something called "Cinematic Mod" to update the look. Classic Valve shooter.
Hard Reset Extended Edition . Bad cutscenes, fun play though.
Just Cause 2 . Chaos Simulator ( and often super cheap on sale )
Mafia 2 . Crime drama open world
Metro 2033 Redux
Metro Last Light Redux
RAGE . Maligned ID shooter because it wasnt doom. Mad Max meets Borderlands?
Red Faction Guerrilla . Destructible environments engine. Always carry your hammer!
Red Faction Armageddon . Destructible Environments. Yeah, carry that hammer.
The Sabotuer . Open world behind the lines in France WW2
Saints Row 2
Saints Row 3
Saints Row 4
Saints Row 4 Gat out of Hell
Shadow Warrior . Brutal stereotypes and humor. Shoot or slice demons in half with a katana. You Got Wang!
Shadow Warrior 2 . Better than the first one
Singularity
Sleeping Dogs
Spec Ops: The Line . Shooter with morality and mind-fvuckery
S.T.A.L.K.E.R. Call of Pripyat . Get the Call of Pripyat Complete Mod
S.T.A.L.K.E.R. Shadow Chernobyl . Get the Stalker Complete Mod
Tron 2.0 . Get the Killer App Mod for easy widescreen. The world inside a computer.
Zombie Army Trilogy . Zombies and WW 2. Grab it on sale.