What Steam Game Have You Spent The Most Hours Playing?

The Binding of Isaac - 198 hours. But I got all the achievements. :D

Dota 2 1004 hours.... and CSS 677... but at least i stopped playing CSS around 5 month ago

DAMN YOU VALVE AND YOUR ADDICTING GAMES!

FTL:95 hours, but I think probably played a lot more Mount and Blade, just not through Steam. Currently all my gaming time goes to Morrowind, a game I played a lot back in the day. 360 sits under the tv but mostly its just used for DVD's and music these days
EDIT: Other non Steam games that would be up there, Fallout 3 and Age of Pirates 2

Counter strike 4200 hours :D

Dota 2 817 hours. I would surely play Skyrim well over 200 hours if it isn't my laptop screwing me over and having trouble running the game so I stopped at 100.

Killing Floor, 860 hrs, followed by MW3 (130 hrs) and both Borderlands (70 hrs each).

Portal 2 - 75 hours.

CS:S over 2020 hours. :D

1. Borderlands - 160.5h
2. Borderlands 2 - 93.7h
3. Counter-Strike - 91.5h
4. Might and Magic: Clash of Heroes - 63.6h
5. Cities in Motion - 47.3h

skyrim 125~

APB Reloaded 705h, that's bad right?

260h on spiral knights

611 hours on Team Fortress 2 since steam has been recording time played.
1044 hours if you include the 433 hours logged by xfire (I stopped using xfire before steam logged time).

214H - GMod

Mount and blade : warband, 113hrs
Civ V : 96hrs

CS:GO 319 hrs

I don't have a counter for how long, but my most played game is probably Dark Age of Camelot, with World of Warcraft as a close second. 3rd, probably Titan Quest Immortal Throne on 328 hours logged. But I know I have a lot more from before I got it on Steam! :)

Awesomenauts with more than 200 hours.

118 hours The Binding of Isaac to get Platinum God :D

Dota2. Right now I have like 170 something hours.

dota 2 1200 hours :D

Torchlight 2, my personal GOTY !

Was playing tf2 from few accounts. If not count idling acounts I've played about 1700 hours since 2009.

counterstrike source 2000+ hours :D best game ever until the orangeboxupdate came

Garry's Mod - 88hours