Kirby: Triple Deluxe
Needs replacement with EX levels for each world, the unique Dedede's Drum Dash mode (and maybe Kirby Fighters mode?).
Kirby's Triple Deluxe is well...a 3D Kirby game on 3DS. The main gimmicks here are the foreground and background as layers (you regularly hop back and forth between them), as well as the collectable Sun Stones. You'll need to collect a minimum number to unlock the world's boss, and all of them in the main level to unlock bonus levels, but collecting all of them isn't very rewarding.