494,6 hours in BF:BC2, of which I didn't play a single minute because my brother owns it. For me it's 221.5 hours in TF2 and more recently 198,8 in Source Filmmaker. Total: 1620,6 hours, 79 games. Does it count the time in offline mode too? (Heh, apparently I played Portal 1 for 41 hours, which is the double of Portal 2…)
Based on Steam's tracking, Skyrim at 199 Hours. It doesn't seem to track properly when launched through SKSE though so that figure is off.
650 hours on dota2, next is Simcity 4 on 39 hours Pales in significance with wow, which must have, between all characters, got up to about 5500hours+
Prototype - 397 hours and a dishonourable mention to; Saints Row 2 - 35 minutes before I decided that it was so badly transferred over to PC that I just quit trying to play it.
Counter Strike Global Offensive. 163 hours. Played Wow for 6 years solid. Wouldnt want to even think about the months of my life lost on that!
Steam has recorded 53 hours on CS:S but I played easily double that before Steam started tracking. Over 75 logged on BF3, no way of checking BC2 atm but I'd say it's similar. Overall ~250 hours on Steam.
BFBC2 - 385 Hours TF2 - 282 Hours I really wish UT99 recorded this stat. I would have had at least 1000 hours per year LOL According to my old XFire account, I played over 900 hours of ut2k4 but that was only for a fraction of the time I played and that was only when xfire was actually running (0_0)
Civ 5 is rapidly gaining as I just got it in the last 3 days and thrown about 10 hours on it already. I'd say BF3 got 350+ hours and I think I've spent a scary amount of time playing Oblivion and Morrowind.
I have around a hundred billion hours on Super Hexagon trying to get past the 30 second mark on the lowest difficulty
Don't have steram infront of my now, but last a recall: Anno 2070 - lower 400s Skyrim - 380 as per over this weekend and still going strong as I'm development a whole bunch of mods atm. House/Collection/Armory/Gleenhouse is new Exterior cell. After that it's AC2 Rev and AC3 - no idea but like 200s high each.
Hmmm... Not sure since I'm at work, but: Left 4 Dead 2: Over 600 hours Left 4 dead 1: around the same (not tracked on steam cuz I played it through Garena for quite a while) Dota 2: Just approaching the 600hr mark