A very good concept, a suggestion, maybe make the stars smaller, or the "gamefield" larger as annoying hitting the boundarys especially when the starts are touching the edge.
Very basic Game, Maybe a few mods like Score, Ammo, as it is way too easy to spam the screen full of shots, Lives so if you let any past. And afer X amount of Targets shot they speed up. Even the basics make for an intresting game, however simple.
 "The Orbit Game"){kind=icon}
 "Simple Ship-Shooter"){kind=icon}