I'll give you outdated playtime on Steam.
Team Fortress 2
76 hrs on record
DOOM 3: BFG Edition
75 hrs on record
Call of Duty: Modern Warfare 3 - Multiplayer
66 hrs on record
Retro City Rampage™ DX (It was AFK, i admit)
44 hrs on record
Call of Duty: Modern Warfare 2 - Multiplayer
42 hrs on record
Garry's Mod
27 hrs on record
Deus Ex: Human Revolution
25 hrs on record
Wolfenstein: The New Order
21 hrs on record
Far Cry® 3 Blood Dragon
21 hrs on record
Left 4 Dead 2
20 hrs on record
BioShock Infinite
20 hrs on record
Battle.net:
WoW
4 years on record
Diablo III
21 hours on record
Non-Clients(pre-Steam):
Doom
19 years on record
Quake
18 years on record
Deus Ex
16 years on record
System Shock 2
13 years on record
Quake 3 Arena
8 years on record
