1. Team Fortress 2 for over 1,400 hours
2. Call of Duty: Black Ops 2 Zombies for over 500 hours
3. Battlefield 3 Multiplayer for over 250 hours
4. Uncharted 2 Multiplayer for over 200 hours
5. Diablo 3+Reaper of Souls over 150 hours

I have not a single regret for all those hours I spent.

World of Warcraft. Over 110days played on my main. Add around 30 to 50 days played on my other charcacters (maybe more).

I can't account for what I did in games pre-internet (Age of Empires, Gizmo's and Gadgets, Mechwarrior 2, Shockwave Assault), but in my adult life there is only one competitor and that is Civilization 4.

3000+ in Runescape.

Think i was pushing 500 days on FFXI....
700 hours civ 5. probably more on Civ IV and 3, Plus some on 1 and 2.
300 hours skyrim.
probably over 300 on FFIV, FFVI, and FFVII

likely not much else is too much over 100.

Oh yeah, forgot my char in WoW. Only one toon, and it's 451 days, 4 hours, 33 minutes

I don't spend a lot of time in one game, because I need time to play other games. But, when I was around 10, I played around 600 hours of Pokémon Yellow and about 500 hours of WoW. Nowadays, the winner is MH4 with 90 hours.

I've probably put over 10,000 hours in FFXI, Runescape, and FFXIV each, easily. Probably much more than that.

Skyrim: 3 Saves around 60-70 hours each.
Terraria: 160 Hours
Final Fantasy XIII: 120 Hours
League of Legends: 1-3 days.

I toned down of gaming recently due to school though.

Destiny of Spirits: 2099 hours in less than a year. Beat that, you dirty casuals!

Actually, don't. It's rather sad. Could have done so much better things with my life (including playing different games)