I'm pretty certain I put over 1000 hours into Oblivion on 360. I was legitimately addicted to that game, holy shit.
I put over 100 hours into Sonic Heroes as a kid, probably Sonic Adventure 2 as well. Hey, I loved Sonic, no idea why.
I was pretty surprised to see that I have about 95 hours in OoT 3D. It's weird, I don't think I did much else in that game besides both the regular quest and master quest, although I know I started a few new games after that which I never finished (3-heart run and another master quest run).