TF2 - 1898.1 hrs :3
Also, IHMO Rise of Immortals sucks.

Dragon Age: Origins
135.7 hrs on record

Counter strike: Source 750.8 hours

(The actual hours I played this game are even higher, since I played the game a lot before steam started tracking gaming hours. I think I would have about 1500 hours of playtime in total on this game.)

Left 4 Dead with 496.8 hours. I should actually have somwhere around 700 hours, but Steam deleted some of them.

CoD: MW2 181.9 hours on record. That feels like a damn lie to be, but their record system isn't 100%, some games I've played a good few hours on say 0.1 (Blur for instance).

Kinda sad about that really but, eh.

Doesn't get much better after that either.

TF2: 172.1 Hours
CS:S 162.8 Hours
DC:UO: 106.2 Hours.

Black Ops Multiplayer 265 hours

Rise of Immortals..

RISE OF IMMORTALS..

ಠ_ಠ

(I played around 50 hrs of Terraria)

Terraria 169.7 hrs on record, never think about it O_O All games

Dota 2.....147.6 hrs on record :)

Dungeon defenders 607.3hrs

TrackMania: United - 168.6 hrs on record

TF2. 2460 hours played.

Killing Floor. By far.

Sid Meier's Civilization V 69.6 hrs on record I don't play much on steam due to lack of time

TF2 1500 hours XD

322 hours on terraria D:

if only i had GW on steam XD played that to death and back.

• Team Fortress 2 - 205.2 hrs on record
• Battlefield: Bad Company 2 - 127.6 hrs on record
• Unreal Tournament 3: Black Edition - 74.5 hrs on record

So many hours on TF2 because of idling :D

322 TF2.. like 60 Terraria, and 41 Busty heartz

Counter strike 1425 hours

Team Fortress 2
1541.6 h

and

DA:O
~100 h

oh, many TF2 players here...
...+1 ;)

GTA IV - 80hrs + -
Next is css, with 50hrs, and garrysmod with 20.

Modern Warfare 2 Mp -> 312.9h

Dota 2 482.6 hrs ( I'm in beta since September and many more hours will come )

css 221 but i played a lot more when steam didn't count (the game was newer) time and plus when i didn't have it i played a lot of ns so about 1500 to 1600 hours