You can find out more about the game here including a game demo (well it’s a kind of DS simulator with the stylus), trailer, interview etc.
Basically it’s a hidden object game but due to the size limitation of the DS, you “scroll” around the screen using the stylus to find the hidden items. I’m not sure how well this will work compared to seeing the whole image on a single screen, but I guess that they must have play tested this a lot and that it does work otherwise they wouldn’t be selling it!
I'm an Indie game developer with a couple of titles under my belt. I've been programming for 23 years on a variety of platforms. Currently I'm using BlitzMax, which is great.