Action games
If you don't play games that much, there is a big chance you have played an action game, e.g. a shooter, at some point. This category is full of games that won't let you get bored.
Shadowgrounds
Tribes 2
Military Operation
Gain Ground
Manhunt
Swords and Sandals 1
Flight Chase
Nation Red
X3 Terran Conflict
Serious Sam 2
Furious Tank
BrainBread
AfterWorld
TorchED
Endless War Defense
DOOM II
RESIDENT EVIL 7 biohazard
Black Star: First Attack
Duke Nukem 3D
Clay Fighter
Dungeon Siege: Yesterhaven
Gore
FizzBall
Sniper Assault
DemonStar Secret Missions 2
