No, it's not Mario Galaxy for DS. :) This homebrew is called Super Mario Galaxies created by Cid2Mizard. Super Mario Galaxies is a shooter where you get to play as Mario floating in space, shooting down Goombas while avoiding bullets and other Mario enemies. It's pretty cool for a homebrew Nintendo DS game, but you'll probably get tired of it after about 2mins. Hopefully the developer of this game will spend some more time to make this game a lot better. We tried this game on a R4DS and it ran fine. Screenshot and link to the NDS rom below.

Download Super Mario Galaxies v0.08