1 Counter-Strike: Global Offensive - 353 hrs

2 The Elder Scrolls V: Skyrim - 219 hrs

3 Fallout: New Vegas - 207 hrs

4 XCOM: Enemy Unknown - 163 hrs

5 PlanetSide 2 - 146 hrs

6 Infinity Wars - Animated Trading Card Game - 91 hrs

7 Space Rangers HD: A War Apart - 82 hrs

8 FTL: Faster Than Light - 55 hrs

9 Warhammer 40,000 Space Marine - 49 hrs

10 AdVenture Capitalist - 42 hrs

Being fair to Space Rangers, I have ~500 hours in the non-steam versions.

1. Real Life - 291,240 hours
2. Team Fortress - 1,516 hours
3. The Elder Scrolls V: Skyrim - 217 hours
4. Half-Life 2: Deathmatch - 191 hours
5. Borderlands 2 - 73 hours
6. Call of Duty 4: Modern Warfare - 66 hours
7. Borderlands: The Pre-Sequel - 56 hours
8. Euro Truck Simulator 2 - 51 hours
9. BioShock Infinite - 44 hours
10. Portal 2 - 36 hours
11. Tomb Raider - 33 hours

Counter-Strike 2,173 hrs on record (between 2007 and 2014; +800-900 hours between 2000 and 2006 on non-steam versions of the game)
The Elder Scrolls V: Skyrim 110 hrs on record
Far Cry® 3 95 hrs on record
Counter-Strike: Global Offensive 31 hrs on record
Thief 25 hrs on record
Hitman: Absolution 25 hrs on record
Mafia II 22 hrs on record
Left 4 Dead 2 18.5 hrs on record
Serious Sam 3: BFE 14.7 hrs on record
Dota 2 14.3 hrs on record

1. Counter Strike: Source - 265 hrs
2. Loadout - 81 hs
3. Saints Row 2 - 23 hrs
4. Day of Defeat: source 22 hrs
5. Civilization V - 18.6 hrs
6. Medal Of Honor Multiplayer - 17.5 hrs
7. Far Cry 3 - 14.8 hrs
8. Dead Space - 12.3 hrs
9. Mafia 2 - 11.8 hrs
10. Alan Wake's American Nightmare - 11.6 hrs

1. Fallout: New Vegas - 175 hrs
2. The Elder Scrolls V: Skyrim - 175 hrs
3. Star Trek Online - 156 hrs
4. The Elder Scrolls IV: Oblivion - 77 hrs
5. Borderlands 2 - 66 hrs
6. Assassin's Creed III - 64 hrs
7. Team Fortress 2 - 55 hrs
8. Saints Row: The Third - 53 hrs
9. Assassin's Creed: Brotherhood - 50 hrs
10. Assassin's Creed II - 48 hrs

1. Dota 2 - 1,022 hours
2. Team Fortress 2 - 267 hours
3. Counter-Strike: Global Offensive - 238 hours
4. Left 4 Dead 2 - 70 hours
5. Garry's Mod - 47 hours
6. Payday 2 - 30 hours
7. Deus Ex: Human Revolution - 23 hours
8. The Witcher 2 - 23 hours
9. Call of Duty: Black Ops II - Multiplayer - 21 hours
10. Batman: Arkham City GOTY - 18.3 hours

1 - Saints Row: The Third [143 hours]

2 - Sleeping Dogs [109 hours]

3 - LEGO MARVEL Super Heroes [91 hours]

4 - Saints Row IV [78 hours]

5 - L.A. Noire [74 hours]

6 - Saints Row: Gat out of Hell [57 hours]

7 - Major Mayhem [51 hours]

8 - LEGO Harry Potter: Years 5-7 [47 hours]

9 - Lucius [41 hours]

10 - LEGO Batman 3: Beyond Gotham [39 hours]

First, keep in mind that while I have been on steam for 6 years, I don't have a lot of spare time between work, forum posting and por...um....movie watching.

Rust - 323 hrs
Beasts of Prey - 29 hrs
Reign of Kings - 25 hrs
Stacking - 20 hrs
Left 4 Dead 2 - 18.5 hrs
Shadowrun Returns - 17.4 hrs
Puzzle Pirates - 15.1 hrs
Infestation: Survivor Stories - 11.3 hrs
Nightmares from the Deep: The Cursed Heart - 8.5 hrs
DayZ - 8.1 hrs

1. Football Manager 2013 - 543 hrs
2. Dark Souls II - 125 hrs
3. Football Manager 2014 - 94 hrs
4. Rust - 67 hrs
5. Grand Theft Auto V - 46 hrs
6. Dark Souls - 41 hrs
7. Team Fortress 2 - 30 hrs
8. Euro Truck Simulator 2 - 29 hrs
9. Assetto Corsa - 28 hrs
10. Bioshock Infinite - 28 hrs

Not as impressive as some of you guys:

1. Tom Clancy's Ghost Recon Phantoms - NA - 347 hrs (played this one even more before it was on steam, so probably clocked close to 1k on it)
2. Payday 2 - 160 hrs
3. Portal 2 - 23 hrs
4. A Story About My Uncle - 9.9 hrs
5. Brothers - A Tale of Two Sons - 9.2 hrs
6. The Wolf Among Us - 9.0 hrs
7. Spec Ops: The Line - 8.7 hrs
8. Bulletstorm - 8.5 hrs
9. Lyne - 8.5 hrs
10. Call of Juarez: Bound in Blood - 7.3 hrs

1. Euro Truck Simulator 2 - 1283 hrs
2. Team Fortress 2 - 1113 hrs
3. Alien Swarm - 223 hrs
4. Spintires - 212 hrs
5. Spiral Knights - 124 hrs
6. Kingdoms of Amalur: Reckoning - 90 hrs
7. The Elder Scrolls V: Skyrim - 79 hrs
8. Saints Row: The Third - 71 hrs
9. Just Cause 2 - 51 hrs
10. Saints Row 2 - 50 hrs

1. Garry's Mod - 378 hrs on record.
2. Age of Empires Online - 165 hrs on record.
3. Arma 3 - 135 hrs on record.
4. Grand Theft Auto V - 103 hrs on record.
5. Starbound - 92 hrs on record.
6. The Elder Scrolls V: Skyrim - 83 hrs on record.
7. Team Fortress 2 - 73 hrs on record.
8. Arma 2: Operation Arrowhead - 69 hrs on record.
9. Insurgency - 63 hrs on record.
10. DayZ - 50 hrs on record.

1. Football Manager 2010
2. Football Manager 2009
3. Football Manager 2014
4. The Elder Scrolls V: Skyrim
5. Crusader Kings II
6. Train Simulator 2015
7. Little Racers Street
8. Mini Motor Racing Evo
9. Tropico 3: Absolute Power
10. Grid 2

1. Day of Defeat: Source - 3641 hrs (My favorite game and a shoutout to the BkW clan!)
2. Dead Island: Epidemic - 539 hrs
3. Dead Island - 141 hrs
4. Windward - 135 hrs
5. DC Universe Online - 114 hrs
6. Peggle Deluxe - 62 hrs (My first game on Steam after Half-Life. I got it for free somehow.)
7. Peggle Nights - 55 hrs (I had to get the sequel!)
8. Team Fortress 2 - 54 hrs
9. Left 4 Dead 2 - 42 hrs
10. Tomb Raider - 34 hrs

1. Binding of Isaac: Rebirth - 136 Hours
2. La-Mulana - 101 Hours (one of my favorite games on steam)
3. Terraria - 78 Hours
4. Dragon Ball Xenoverse - 72 Hours
5. Borderlands 2 - 58 Hours
6. Fallout: New Vegas - 50 Hours
7. Risk of Rain - 40 Hours
8. Binding of Isaac - 35 Hours
9. Rogue Legacy - 16.7 Hours
10. Freedom Planet - 15.8 Hours

I really like Roguelikes now, especially thanks to Rebirth.

lets see here
1.) Arma 2: Operation Arrowhead | 416 hrs
2.) Arma 3 | 358 hrs
3.) War Thunder | 282 hrs
4.) Company of Heroes 2 | 139 hrs
5.) Heroes and Generals | 125 hrs
6.) Sins of a Solar Empire: Rebellion | 84 hrs
7.) Terraria | 75 hrs
8.) Rising Storm/Red Orchestra 2 Multiplayer | 32 hrs
9.) Sid Meier's Civilization V | 27 hrs
10.) Men of War: Assault Squad 2 | 22 hrs

Welp dats it =^.^=

The Sims 3 - 460.09
Marvel Puzzle Quest: Dark Reign - 137.64
Age of Empires II: HD Edition - 91.65
Left 4 Dead 2 - 84.95
Sniper Elite V2 - 62.37
Tropico 5 - 61.02
Fallout: New Vegas - 42.34
Microsoft Flight - 28.69
The Walking Dead - 28.02
Tropico 4 - 26.59

1.Garry's Mod - 280 hrs
2.The Elder Scrolls V: Skyrim - 118 hrs
3.Team Fortress 2 - 64 hrs
4.Borderlands 2 - 38 hrs
5.Payday The Heist - 33 hrs
6.Star Wars: Knights of the Old Republic - 31 hrs
7.Star Wars Jedi Knight: Jedi Academy - 24 hrs
8.Saints Row IV - 23 hrs
9.The Elder Scrolls III: Morrowind - 22 hrs
10.Mafia II - 21 hrs

1) Dota 2 - 1,755 hrs
2) Team Fortress 2 - 70 hrs
3) Path of Exile - 56 hrs
4) Recettear: An Item Shop's Tale - 29 hrs
5) Audiosurf - 29 hrs
6) Warframe - 27 hrs
7) Left 4 Dead 2 - 19.6 hrs
8) Counter-Strike: Global Offensive - 19.1 hrs
9) Magical Battle Festa - 15.3 hrs
10) Awesomenauts - 13.9 hrs

There should be Endless Legend 30-40 hrs but steam doesn't track demo access.
This also reminds me how much time I killed and wasted on looking at pixels, good times often though :^)

1. Spelunky - 318 hrs
2. Dark Souls 2 - 159 hrs
3. GTA V - 141 hrs
4. CoD Ghosts MP - 99 hrs
5. Starbound - 89 hrs
6. Might & Magic: Heroes VI - 62 hrs
7. Assassin's Creed IV Black Flag - 49 hrs
8. XCOM: Enemy Unknown - 43 hrs
9. FaeVerse Alchemy - 37 hrs
10. Rust/PvZ/FTL - 35 hrs

1. Left 4 Dead - 3742 hours
2. Left 4 Dead 2 - 2846 hours
3. CoD: Modern Warfare 2 Multiplayer - 1047 hours
4. Killing Floor - 351 hours
5. Dungeon Defenders - 243 hours
6. Borderlands - 164 hours
7. DayZ - 147 hours
8. Orcs Must Die! 2 - 105 hours
9. No More Room in Hell - 88 hours
10. ORION: Dino Horde - 75 hours (haven't played the Prelude update)

Stopped playing L4D1 for a couple years but recently started playing campaign again. Dungeon Defenders is so fun, I'm reinstalling it right now. You could say I want the DD.

Counter-Strike: Source .....................5,020 hrs on record
Counter-Strike: Global Offensive ....1,364 hrs on record
Team Fortress 2..................................759 hrs on record
Call of Duty: Black Ops II - Multiplayer.......407 hrs on record
Depth..........................................................189 hrs on record
Counter-Strike............................................187 hrs on record
Crysis 2........................................................167 hrs on record
Call of Duty: Modern Warfare 2 - Multiplayer.....133 hrs on record
Call of Duty: Black Ops - Multiplayer.........110 hrs on record..
PAYDAY: The Heist.........................................94 hrs on record

Unepic - 81h
Kingdoms of Amalur: Reckoning™ - 30h
Rogue Legacy - 27h
Far Cry® 3 - 18h
Far Cry 2 - 16.7h
Costume Quest - 16.4h
XCOM: Enemy Unknown - 13.3h
Brütal Legend - 11.5h
Card City Nights - 10.1
Hero of the Kingdom - 8.8h

1. Dota 2 - 731 ore in totale
2. Counter-Strike: Global Offensive - 440 ore in totale
3. No More Room in Hell - 174 ore in totale (This is a bug i never played more than 5 hours this game)
4. Dungeon Defenders II - 162 ore in totale
5. PAYDAY 2 - 111 ore in totale
6. Terraria - 71 ore in totale
7. Team Fortress 2 - 56 ore in totale
8. Ys Origin - 40 ore in totale
9. Nosgoth - 38 ore in totale
10. Super Sanctum TD - 35 ore in totale