It's hard to come up with a favourite game, but the game i play most at the moment is on xbox 360, a little game called Call Of Duty: Modern Warfare 2.
the games that ive played for the longest were the pokemon games because i was 12 and just introduced to video games or rather those were the only games i played. i remember i played diamond or emerald or ruby for 212 hours. but the best game for 360 is Battlefield Bad Company 2. ive played it for 98 hours.
I have alot of favorite games, but as far as my most recently played favorite, it would have to be Lost Planet 2. I thought it was pretty cool, and addicting, at least on co-op. The online aspect wasn't all that great, tho.