Never played a game on 360 that is only 6 hours. But I did hear King kong was very short, I think I heard its like 6-8 hours. But thats also on every other platform.
There's a few games I might get in the future. No More Hereos if it gets a decent rating at Game Informer, or atleast a 75 at Metacritic, maybe only 70. Sadness for sure if it looks good once I see some screenies. Mario Kart if I hear controls are good. Bully, thats gonna be good. Brothers in Arms if its not on Xbox. Disaster: Day of Crisis if it gets good reviews. SSBB is coming out, but I was never really liked Melee to much so ill skip it.
But still the 3rd party games are no where near the competitors.