1. Call Of Duty Modern Warfare 2 (One month of hours's play)
2. Battlefield 3 (Only with friends)
3. Minecraft (Online on Xbox)
4. Call Of Duty Black Ops (Only for Zombies)

I think it's all

PC: Age of Conan
Wii: Rock Band II , Super Smash Bros. Brawl
Nintendo Handhelds: Pokémon Series, Fire Emblem Series

Final Fantasy XIII
Final Fantasy XIII-2
Fallout New Vegas
Skyrim
FIFA

each game already played more than 100hours..skyrim and fallout maybe reaced to 200-300 hours

i play

monster hunter 3 and 2, and medal of honor (heroes) on my psp
and on my ps2 is need for speed (most wanted) and innocent life
on my pc i play slender man plants vs zombies,and a little bit of dota with couzins

I think I have spent a good amount of time playing Halo 4 online but I think RPG's take all of my hours

Ni no Kuni - 48 hours so far

I replayed FFXIII - took about 50 hours

Looking at my 3DS data log, it seems that all of my Zelda games combined that I have played on that console are well over 70 hours! But that's nothing compared to the hundreds of hours that I have spent playing Pokemon!

Home consoles (PS1+2+3, DC):
1. Persona 4 (PS2) - more than 800 hours
2. Persona 3 FES (PS2)
3. Shenmue II (DC)

iOS:
1. Taiko no Tatsujin Plus
2. Steins;Gate (Kurisu is mai waifu)
3. Final Fantasy III

PC: (lol, pes overkill... and I suck at soccer)
1. PES 09 - 112 hours
2. PES 11 - 105 hours
3. PES 10 - 97 hours