What Steam Game Have You Spent The Most Hours Playing?

TF2 1460 hours

1542 hours on football manager 2010

GMod and Team Fortress 2.

Top 3 :)

1. Batman: Arkham Asylum GOTY Edition - 117.9 h - almost 100%, but my save file got corrupted :(
2. The Witcher: Enhanced Edition - 67.8 h - I want to play TW2 but I have many games with 0 hours
3. Left 4 Dead 2 - 63.7 h - One of the first games I bought :)

Star Wars: Knights of the Old Republic - 78.2 h

ArmA 2: Operation Arrowhead .. mostly because of DayZ but i've been playing a lot of co-op missions with friends too

Bulletstorm ofc 127 hrs. Online play is a blast! If Halo: Combat Evolved was a steam game already..I'd have you all beat.. not in hours, but years. :P

inb4 cs 1.6, dota 2 , tf , and multiplayer games

gmod

counter strike 1.6 and team fortress 2 :P

Realm of the Mad God : 882.2 hrs on record and then next game is Killing Floor 214.5 hrs on record

Alien Swarm 542 hrs

Spiral Knights 455.9h

Binding of Isaac. 523 hours.

Garry's mod

source filmmaker 332.8 hours
team fortress 2 244.3 hours

borderlands and witcher

1500 HRS Counter Strike 1.6

hand job +10000 days played

TF2. 1646 hours.

about 210 hours on MW3, and then near 30 on the binding of isaac

Battlefield Bad Company 2 with around 130 hours...

Bloodline champions - 45.2h
C9 - 34H

Counter Strike 1.6 over 2000 hours on steam .