#21 - Mario Kart: Double Dash! (GC)
As guessed by no-one (seriously, all these Nintendo fans in this thread and not one of you picked up on this!) Anyhow, MKDD is the second best local multi-player game I've ever played and for that reason alone deserves such a high spot in my list. Add in a mix of great and memorable tracks, really interesting double-kart mechanic and that traditional-but-still-great Mario Kart gameplay and you've got yourself a winner. Definitely the best in the series.
Clue for my #20 - JRPG with a very 'western' (hint: not what you'd first think) design.