Most time you've ever put into a game

[QUAKECore89]

1) Quake 3 Arena: 15 years. Still on.
2) Unreal Tournament: 14.5 years. Still on.
3) Duke Nukem 3D: 14 years. Still on.
4) Half-Life 1: 12 years. Still on.
5) Half-Life 2: 10 years. Still on.
6) World of Warcraft: 4 years. Started from 2006 to 2010 ended.