Tell me the Game on which you have spent the most hours on steam. xD

TF2: 1,253 hrs

On Steam, CoD MW2 Multiplayer at 151.5 hours, then Skyrim at 84.8 and Fallout: New Vegas at 84.4.
I wonder how many hours I've played Minecraft. World of Warcraft beats them all though, with way over 4000, possibly over 5000 hours (over 8.5 years that is).

cs 1.6 = 374 hours
cs:source = 513 hours but it's mostly played by my lil bro

Borderlands 290
Torchlight 228
Plants vs Zombies 179
Serious Sam 3:BFE 132
King's Bounty: The Legend 109

My top 5 are:
TF2 - 207hrs
The Binding of Isaac - 123.3hrs
CS:GO - 40.3hrs
Blacklight: Retribution - 35.3hrs
Torchlight 2 - 25.2hrs

Top 5 of all time
Top 5 this week

The Elder Scrolls V: Skyrim -> 73.9 hrs on record

And i'm not finished with it yet. I love it!

Something that is called Counter Strike, have not touched the game in a while.

DC Universe Online - 515.5 hrs

Crusader Kings II - 437 hrs on record. Fascinating game, really.

Tf2 with 587 hours

Stronghold Kingdoms 154 hrs.

Garrys Mod - 122.8 hours

Crusader Kings II around 110h. Still haven't finished a game :3

The Binding of Isaac 96 hrs + about 50 hrs in offline. Killing Floor - 170 hrs. Borderlands 2 - 100 hrs. Arma 2 - 200 hrs+. Anno 2070 - 70 hrs. Far Cry 3 - 70 hrs.

CoD WaW, 139hrs. Many hours of custom zombies with friends.

for me its CS:S over 350 hours played so far

50 hours for PAYDAY

Dear Esther about 700 hours.

TF2

Team Fortress 2 - 223 hours.

Terraria 100 hours

Garry's mod 188 Hours ^__^

Skyrim, with 200.5 hours...
Next in line would be Torchligh II with 35.8 hours.

And yes, I know I skipped TF2, but most of those 90 hours have been spent idling, with probably less than 10 hours played.

Counter Strike 1.6 - 1270h ;)