Mass Effect hasn't gotten boring yet even after 18 play throughs
Ratchet and Clank, the ones before A Crack in Time, I don't know, the spaceship segments are just uninteresting and are way too long
I've sunk a hundred hours into League of Legends too, but hey its free
I have also had a ton of fun playing Mirror's Edge a few times, I wish there were more escape- like games, Mirror's Edge pulled off escape scenes very well
and Fallout 3...
ah Fallout 3, never gotten bored yet, 300+ hours or something ridiculous like that