What Steam Game Have You Spent The Most Hours Playing?

TF2: 2,093 hrs

So far it's TF2 at 158 hours, but since I've all but stoppis playing TF2 and have logged 54 hours in Skyrim since I started playing a week ago, I imagine Skyrim is going to pass it soon.

I wish there was a way to check League of Legends play time, it would be interesting to know.

Killing Floor. 600+ hours and counting

Zombie Panic Source - Mod
Mount and Blade: Warband - game

101 hours in Skyrim so far

The current reigning champ in my library is Dungeon Defenders at 452 hours, but in only a month I've logged 123 hours on Magic the Gathering: Duels of the Planeswalkers 2013, so I expect that to far surpass DD pretty soon.

skyrim, 100.4hrs. Then my save got corrupt, now im back to a save from about 10hrs in :(

Dota 2 or Civ 5

Not sure which one, they are near the same amount of hours.

1. Team Fortress 2 - 392.9 hrs

2. Left 4 Dead 2 - 125.9 hrs

3. Plants vs Zombies - 100 hrs

I love me some goddamn PvZ.

Dungeon Defenders at 700 hours.

css 3000 hours

CS:S about 250 hours, but it's CS:GO time, so I'm sure that I'll break that record quickly!

Team Fortress 2 at over 700 hours. I don't even idle. I don't play that often anymore either.

Tf2 at 229 hours.

Civ V 100+

I was suprised I thought I would see it more on this list. Interesting.

Killing floor over 900 hours. It was my very first game I bought on Steam

TF2, 578 hours

Call of Duty: Modern Warfare 2 - Multiplayer
1,395.7 hrs on record (Around 200 hours of IDLE - I was hosting ESL games)

Team Fortress 2
421.7 hrs on record (Probably 40% of them are IDLE)

Terraria
128.8 hrs on record

Left 4 Dead 2. 345.4 hrs on record

Borderlands 2 - 1020 hours played, a lot of which was spent with the program open but not actually playing. I do have 4 lvl 50 characters though and full legend sets for all.

Just Cause 2 - 150.0 hrs
Saints Row: The Third - 78.1 hrs
DiRT 3 - 71.0 hrs
Spiral Knights - 60.0 hrs
Mafia II - 46.4 hrs
They Bleed Pixels - 30.5 hrs
Warhammer 40,000: Dawn of War - Game of the Year Edition - 22.5 hrs

And many more...

Team Fortress 2, Super Meat Boy, and Dungeons of Dredmor are nearly tied for me. TF2 is at 68 hours.

Red Orchestra 2 over 300 hours till now...

Mount and Blade and the Warband sequel

Dungeon Defenders got 3950 hours in it :)