I put over 1500 hours into Little Big Planet 2 BUT...thats not my most played game.

I played EverQuest 1 for 12 years, and had well over a YEAR of actual playtime...thats over 9000 Hours.

750+ hours on Halo 4 and I'm still playing it. Could rise to 800 by the time the MCC comes out.

damn, i fortgot The legend of zelda OOT, i expend on it like 300 hours, it is a materpiece of software...

well single player , it would probably be heroes of might and magic iii

multi definitely counter strike .. can't count

9k+ hours in Runescape
4k+ hours in Maplestory

Hell yea!  Socom 2 was literally the only game I played for about 2 years.  Even when Socom 3 was released I played more S2.

Probably had around 500 hours between multiple names.

Others:

Monster Hunter Tri and Dark Souls were both in the 300-400hr range.  

Cod Modern Warfare 200+hrs

My most played game would probably be COD4. Easily 1500+ hours.

I have around 4 or 5k of hours in Lineage... Since I played it from 2006 to 2010...

MMO are very life consuming, the second game is probably Digimon World 3 with 230h and its does not come even close.

sadly like 200 days on swg

1350 on Halo 3