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.
Stoink
The Expendabros
Call of Duty Black Ops
War of Insects
Tanki X
Unvanquished
Naruto Go
Nostale
State of War
Hunting Unlimited 2010
Alien Zap
Hard Time
Hitman: Contracts
Odamex
S.T.A.L.K.E.R. - Shadow of Chernobyl
Operation Alpha Zylon
Max Payne 2: The Fall of Max Payne
Gears of War
Battlefield 4
World of Tanks Blitz
Medal of Honor™: Pacific Assault
War Thunder
RAW ULTIMATE IMPACT
Half-Life 2
Rainbow Six Siege
Battlefield 2
Quake 4
Call of Juarez - Bound in Blood
Rappelz
Discover FDM
Add-on support
You can get add-ons that download files/video from arbitrary websites.