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.
Dekaron
Alien Outbreak 2 - Invasion
Vogue Tales
PREY
WWFRAW
Plummit
Hounds Last Hope
F.E.A.R. 2: Project Origin
Adventure Craft
Deadly Stars
Invading Force3
Eve
Torque 3D
Beetle Bomp
Souptoys
The Incredibles - When Danger Calls
Core Fighter Demo
Mexican Motor Mafia
Tanks Evolution
WARMODE
Warsow
Sonic 3 DBlast
Calibur Of Spirit
Alien Arena
Toribash
LEGO® Batman: The Videogame
Hedge Hogs in Space
XMen
Quest for Glory II: Trial by Fire
DOOM 3: Resurrection of Evil
Discover FDM
Add-on support
You can get add-ons that download files/video from arbitrary websites.