I'm not sure you can consider a sequel that the most recent game in the series just came out last year a sleeper hit, because there's going to be people who know about it and such. Course I've always considered a sleeper hit a game that does well that no one saw coming, and not necessarily a game that does well that wasn't hyped.
Also, Endless Ocean was released in NA, so it's out everywhere now.
My sleeper hit prediction is probably Boom Blox.







