Tie between MAG, Heavy Rain and Gran Turismo 5. I could see myself putting in hundreds of hours into each game

Mass Effect 2 or an online based game(ex. MAG), I'd probably play it more than 5 other games that I really want combined.

Modnation racers as it seems it will have the replayability factor of LBP.

Starcraft 2 :D

Metroid Other M UNLESS I know 100% without a doubt Zelda Wii is coming out in 2010, however, considering that is unlikely, then Metroid:OM is it.

oooohhh forgot one thing. IF Battlefield 3 comes out then it would actually have to be that one as the online multiplayer puts it at the most replayability.

Gran Turismo 5

Final Fantasy XIV

>_> seriously

That would be a nightmare!

I think I would choose No More Heroes 2.

either ffxiii or gt5 since if i'm only gonna buy one game in 2010 it should be one that would give hours and hours of play.