Probably Gears of War (360), I can't think of another game.

Pokemon Yellow, 100 hours, maybe another 100 bertween blue and red too, had to get all 151.

City of Heroes (PC)

1.) Final Fantasy VII (Beat it at least 17 times, 10+ of those files with the clock overstopped at 99.59.59)

2.) Rock Band (Incountable amount of time put into this game... but I know it isn't up to FF7)

3.) Pokemon Ruby (My clock says 220.00 hours EXACTLY)

4.) Final Fantasy X (The clock says like 270ish hours, but that was spread between me and my sisters gameplay)

5.) Dark Cloud 2 (The clock says about 130ish hours)

Final Fantasy X on PS2. I bought it in 2002 with my ps2. I played it on and off. Go to a part where it took me months to beat a boss. Trade the game and got ripped off by gamestop, bought it back and two months ago I just killed Seymour. However, I am still nowhere near the end of the game.

I remember Football Manager 2005 (PC) telling me I had played one savegame (and I had around 6) for more than 6 days, that's around 150 hours, plus all the other saves it should total around 250 hours. I probably played more Pro Evo 5, but I can't be sure

Super Smash Bros. Melee: Around 500 hours. Ah good times.

1.5 year everyday play of Diablo 2.

-A total sum of like 350 hours on FFX.

Everquest

Street Fighter II on SNES. I still play it often to this day so you do the math.