A game that flew completely under my radar was Reflection, a DSiWare game published by Konami. It’s a platformer with an interesting mechanic.
On the top screen is one view of the level, but on the bottom screen is a reflected version of the top. Players will concentrate on one screen, but may need to look at the other to overcome an obstacle onto on the first screen. That’s in reflection mode. In shadow mode, which is harder, the top screen is one half of the character and the bottom screen is its shadow. When either the character or shadow drops into a bottomless pit or somehow gets left behind, it’s game over. It’s like playing two platformers at the same time. I’d love to play more of this game — it’s a great twist to the usual mechanics of a platformer and makes for decent but logical puzzles.