It's not a copy of the homebrew, Shooting Watch is property of Hudson.
On the splash screen of the homebrew we actually put "Original concept by Hudson"
The idea for the homebrew was just to have a shooting watch on the DS.

To be honest i was expecting much more from the official DSiWare game. I would like to have seen stuff like a caravan shooting mode added, which could have included some of the old PC-Engine 2 and 5 minute gameplay modes from the soldier series. You cant really argue for 200 points though.