1. Dragon Age: Origins - 134 Hours 
2. Plants vs Zombies - 62 Hours 
3. Team Fortress 2 - 48 Hours 
4. Torchlight - 24 Hours 
5. Warhammer 40k: Dawn of War 2 - 20 Hours

1.  Borderlands - 274 hours
2.  Dragon Age - 84 hours
3.  Mass Effect 2 - 72 hours
4.  Mass Effect - 67 hours 
5.  Civ V - 56 hours

TF2- 109 hrs

BC2- 88 hrs

ME2- 74 hrs

Borderlands- 59 hrs

ME- 49 hrs.

1. Counter Strike 1.6 - 71 hours 
2. Left for Dead 2 - 46 hours
3. Garry's Mod - 30 hours 
4. Torchlight - 22 hours
5. Dragon Age: Origins - 10 hours 
 
I really need to get back to Dragon Age...

TF2 is more than the other games combined, but: 
 
TF2 
Plants vs Zombies 
Fallout 3
Half-Life 2 
World of Goo 
 
I'm starting to get embarrassed about the TF2 number.  I love the game, but man... that's a lot of my life spent in a single game!

According to Steam:

1. Garry's Mod - 54 hours
2. Plants vs. Zombies - 44 hours
3. Mayhem Intergalactic - 17 hours
4. Half-Life - 8 hours
5. Recettear: An Item Shop's Tale - 8 hours
6. Uplink - 8 hours
7. Grand Theft Auto III - 6 hours
8. Braid - 5 hours
9. Audiosurf - 5 hours
10. Chime - 4 hours

 Left 4 Dead - 381.6 hours  
 Insurgency - 339.2 hours 
 Counter-Strike: Source 135.1 hours 
 Borderlands - 104.7 hours 
Saints Row 2 - 75 hours
 
TF2 also has 538.1 hours, but I guess game time tracking wasn't enabled around its release.

i have 1355 hours in TF2 
 
ATLEAST 800 are game-time

Team Fortress 2   
 

Counter Strike Source: 239 
Empire Total War: 154
Garry's Mod: 130
World in Conflict Soviet Assualt: 73
Counter Strike: 63
 
and like 200 more hours spread out on other games

1. Dragon Age: Orgins 47 Hours played
2. Empire: Total War 39 Hours played
3. Mass Effect 2 23 Hours played
4. Tropico 3 18 Hours played
5. Civilization 5 11 Hours played

mount and blade -190 hours ( I have no idea how I hit this number that seems crazy high)
left 4 dead - 135 hours
Team Fortress 2 - 110 hours
Mass effect - 60
STALKER Shadow of Chernobyl - 53

1. ArmA 2 Operation Arrowhead - 560 hours

2. ArmA 3 Alpha - 33 hours

3. Mount & Blade Warband - 14 hours

4. Garry's Mod - 9 hours

5. Max Payne 3 - 9 hours

1. Skyrim - 128 hrs

2a. Diablo 3 - 98 hrs (not on steam but felt it should be included anyways)

2b. Borderlands 2 - 63 hrs (mostly SP, no DLC)

3. Far Cry 3 - 57 hrs

4. Saints Row: The Third - 36 hrs

5. Darksiders 2 - 32 hrs

Football Manager 2013.

Thread necroes!

Stats update :)

1. DOTA 2 - 861h

2. DoW 2 - 373h

3. DoW 2: CR - 231h

4. DoW 2: Retribution - 215h

5. Space Marine - 146h

1. Team Fortress 2 - 318 hours
2. Star Wars Battlefront 2 - 163 hours
3. Dota 2 - 74 hours
4. Gmod - 56 hours
5. Killing Floor - 42 hours

1. Borderlands - 98.1 hrs

2. FTL: Faster Than Light - 64.9 hrs

3. Torchlight II - 50.5 hrs

4. Mass Effect 2 - 42.6 hrs

5. Prison Architect - 39.7 hrs

1. Dark Souls - 310 hrs
2. Mount and Blade Warband - 301 hrs
3. Skyrim - 226 hrs
4. Team Fortress 2 - 104 hrs

1. Avernum: Escape Form the Pit - 76 hours
2. The Elder Scrolls V: Skyrim- 75 hours
3. The Elder Scrolls III: Morrowind- 69.4 hours
4. Sid Meier's Civilization V- 56.5 hours
5. Mount & Blade: Warband- 51.1 hours

Open world up in this bitch!

1. Civ V: 237.4 hours.

2. Just Cause 2: 181.6 hours.

3. Terraria: 168.1 hours.

4. Skyrim: 157.7 hours.

5 Borderlands 1: 127.6 hours. (BL2 is getting close, however.)

That's just for Steam. Now, my all time highs would be Burnout Paradise, Minecraft, and World of Tanks, all in excess of 500 hours.

It's worth mentioning that my TF2 playtime is only about half of the amount of time I've played Street Fighter 4 and it's iterations across 360, PS3, and PC.

• Team Fortress 2 - 865.0 hrs on record
• Dark Souls: Prepare to Die Edition - 265.8 hrs on record
• The Elder Scrolls V: Skyrim - 261.9 hrs on record
• Batman: Arkham Asylum - 135.3 hrs on record
• Sid Meier's Civilization IV: Beyond the Sword - 118.4 hrs on record

The scary thing is, I never idled for hats...

Star Trek Online 857 Hours(a lot of this time is the game just running in the background)

Civilization V 486 Hours

Crusader Kings II 168 Hours

Sim City 4 Deluxe 44 Hours

X-COM 2.3 Hours(just bought it last week)

1. Counter-Strike: Global Offensive - 941 hours
2. Dota 2 -910 hours
3. Counter-Strike: Source -164 hours
4. Battlefield: Bad Company 2 - 120 hours
5. Rift - 96 hours
   
   
   Proceeding to be depressed at my lack of any form of life.

1. Skyrim - 47.9
2. Doom 3 BFG (yes, really; remember that 1 and 2 are included and I use them as podcast games) - 44.4
3. Borderlands - 40.2
4. Sleeping Dogs - 37.7
5. Dragon Age Origins - 32.5

Actually, Torchlight 2 ought to be fourth and Deus Ex Human Revolution ought to be fifth because my brother has played those latter two a fair bit.

Skyrim

New Vegas

Dragon Age Origins

Defense Grid (How the hell did I rack 124 hours in this game?)

Mass Effect 2

1. Grand Theft Auto San Andreas - 73 hours

2. Civilization V - 53 hours

3. Skyrim* - 46 hours

4. Fallout New Vegas* - 30 hours

5. XCOM: Enemy Unknown - 25 hours

*These times are in addition to the hundred-plus hours I've played of both on my Xbox.

Currently it's:

• TF2 - 245 hrs
• Fallout: New Vegas - 81 hrs
• Borderlands 2 - 51 hrs
• Borderlands - 50 hrs
• Torchlight 2 - 42 hrs

According to Steam:

1. Borderlands 2 - 128 hours

2. Red Faction: Guerrilla - 109 hours

3. Global Agenda - 96 hours

4. TF2 - 66 hours

5. Deus Ex: Human Revolution - 63 hours

I know that some of the games on my list don't have the right times though (for example says I haven't played HL2: EP1).

EDIT:

Looked at my Xfire and Raptr accounts and it's more like:

1. League of Legends - 463 hours

2. The Matrix Online - 416 hours

3. Borderlands 2 - 128 hours

4. Red Faction: Guerrilla - 109 hours

5. Global Agenda - 96 hours

• Empire: Total War 457 hrs
• Darkest Hour: a Hearts of Iron game 233 hrs
• Victoria II 195 hrs
• Dark Souls 144 hrs
• Crusader Kings II 100 hrs

• Team Fortress 2 - idling borks my hours counted, but it's probably in the neighborhood of 100-120 hours without idling.
• Dead Island - simple co-op game for when friends just want to smash zombies without too much strategy; 65 hours
• Torchlight (1) - 44 hours
• Sleeping Dogs - 42 hours
• Star Wars: Knights of the Old Republic (1) - 26 hours

Yeesh. I need to play more of my Steam games

And it's time to update my top 5.

1. Team Fortress 2 - 338 hours. Haven't played it in any regularity in about a year.
2. SimCity 4 Deluxe - 214 hours. Most of that in a span of a month.
3. Terraria - 195 hours. Cracks the top 3.
4. Audiosurf - 73 hours. Dropped 2 spots.
5. Borderlands 2 - 67 hours. Knocks off Borderlands down to #6.

1. Fooball Manager 2011 - 606 hours
2. Fooball Manager 2012 - 347 hours
3. Fooball Manager 2010 - 283 hours
4. Fooball Manager 2009 - 191 hours
5. Fooball Manager 2013 - 149 hours

I think I need to reevaluate my life...

1) Civilization 5 - 808hrs

2) Crusader Kings 2 - 653hrs

3) Mount&Blade: Warband - 439hrs

4) Total War: Shogun 2 - 224hrs

5) Team Fortress 2 - 204hrs

6) The Elder Scrolls V: Skyrim - 201hrs

1. Orcs Must Die! 2 - 32hrs
2. Torchlight II - 26hrs
3. Civ V - 14hrs
4. Bastion - 7hrs
5. Hotline Miami - 5hrs

....it's pretty obvious I'm mostly a console gamer...

1. Mount & Blade Warband: 643 hrs

2. Left 4 Dead: 245.6 hrs

3. Dota 2: 203.8 hrs

4. Left 4 Dead 2: 173.1 hrs

5. Skyrim: 156.2 hrs

TF2 (392 hours), Borderlands 2 (322 hours), Borderlands 1 (193 hours), Civ 5 (192 hours), Mass Effect 2 (128 hours) (because I've played through it, like, 4.5 times)

1. Skyrim - 133.

2. Terraria - 114.

3. Command and Conquer 3 - 100.

4. Saints Row 3 - 98.

5. Half Life 2 - 91.

AI War: Fleet Command, World in Conflict, Borderlands 2, Rome: Total War and Neverwinter Nights 2 are 5-10.

I've played even more Half Life 2, Skyrim and Saints Row 3 than that, though. My first Steam account forever ago for Half Life, and console for Skyrim and Saints Row 3.

1. Team Fortress 2 - 1844hrs without a moment of idle, because why would I need to when I like playing it so much
2. Skyrim - 204hrs
3. Torchlight - 204hrs
4. Terraria - 204hrs ... that's a weird tie, isn't it?
5. Borderlands - 194hrs

And then it's Borderlands 2, Space Pirates and Zombies, Spacechem, Civ 5

If I didn't have to go out shortly, I'd now totally go and play more TF2... just thinking about it makes me want to play heheh.

Garry's Mod - 237

Counter Strike Source - 233

Dota 2 - 200

Zombie Panic! Source (Game's so damn dumb) - 187

Team Fortress 2 - 186

1. stronghold kingdoms
203 hours
granted the majority of that is being idling in the background or running while i was either away or sleeping since i forgot to close it down. i would guess that at most i have played it for about 5 hours total.

2. anno 2070
123 hours

3. the last remnant
88 hours

4. the settlers 7: path to kingdom gold edition
82 hours

5. dota 2
73 hours

1. Dark Souls - 156 hours

2. Skyrim - 145 hours

3. Total War Shogun 2 - 120 hours

4. IL-2 Cliffs of Dover - 101 hours

5. DOTA 2 - 92 hours

A lot of time in other games was lost because I either use a mod launcher that bypasses steam(or ArmA 2 would be #1) or because I played it before Steam counted time.

1. Fallout: New Vegas - 207.6
2. Borderlands 2 - 196.2
3. Skyrim - 136.1
4. Dark Souls - 70.5
5. Fable 3 - 67.9
6. Assassin's Creed 3 - 67.7
7. Dungeons of Dredmor - 67.5

I totally forgot people idled (or still idle?) for items. I have about 300 hours logged, and haven't really touched it in the last two years.

OH GOD THIS THREAD IS ALMOST THREE YEARS OLD WHY WOULD YOU DO THIS

Also, to update: I'm at 786 TF2 hours (so adding in those untracked ~250 that'd put me at just over a thousand) and 819 Dota 2 hours.

1. Team Fortress 2 - 146 Hours
2. Garry's Mod - 59 Hours
3. Modern Warfare 2 - 56 Hours
4. Left 4 Dead 2 - 44 Hours
5. Audiosurf - 38 Hours

My most played PC games all aren't on Steam, like Swtor (160 hours), Maplestory (160 hours+ (woops)), War Craft 3 (400+ hours), etc. Also don't think my Audiosurf time is very accurate, really it's probably closer to around 75 hours, and Beat Hazard is around 50. Also kind of sad to see TF2 is still number one for me by such a large margin, considering I haven't really played that game in about three years.