My favorite XBLA title? Castle Crashers. I know this seems like a corny answer but it's true.
When I was kid, I used to play to play all the old school 2D beat-em-ups. If it was out in America, I probably owned it and might of even had multiple copies of it. Especially if it was a game like Final Fight, I must of had at least 4 copies of it because I played them to death.
Now that I have a younger brother, I wanted to pass on my love for these types of games. Unfortunately my brother was too keen on playing the older games(because this was old). I wasn't very successful searching for the beat 'em up that would finally grab him and help him understand my love for the genre, so I gave up.
Then when castle crashers came out I decided to give it one more try. I figured that maybe the games humor would appeal to him more, and it did.
He instantly fell in love with the games art style and humor, though I'd like to meet the child that can resist the call of pooping owls and dears that shoot across the screen. We haven't played much since it came out because of school and he's moved onto trying other classic beat 'em ups (and new ones he kinds on the computer).
If I won the contest, I'd give him the Castle Crashers Knight since he's proven that he's superior to me at the game and I'd probably spend the points on alot of the older games. I'd love to get him hooked on games like Metal Slug and Golden Axe.