I got Halo 3 the day of it's release. I completed it on single player legendary campaign in a couple of days (don't get me wrong, it was no easy task) and collected all the skulls for the armour.
I played it online for about a week but after that I havn't really got back into it. I play it occasionally when my friends come over but not that much.
Don't get me wrong, I played the hell out of Halo 1 for PC, and I love FPS's. Unreal Tournament GOTY was the first game I ever got really addicted to on the PC.
I just can't get back into Halo though. Why is it so great?