It's not bad for a demo, really. In fact, it's looking swell thus far. This here is French developer Bilou's DS homebrew game, Bilou in Green Woods Demo, aka GEDS Demo 05/20/09 Update. This update showcases his most up-to-date pixel art.
What do you have to do? Well, just collect as many apples as you can. If the word "GREAT" flashes on your screen, it means you've got 16 of them. Don't be confused though. The hero is the blue critter, not the yellow Goomba-looking ones. You won't get hurt while jumping, but it's safe to assume that you will get injured if you bump into the baddies.
Download: Bilou in the Green Woods Demo