NES. My grandma has that system.
Never played Galaga, is it fun? I like Duck Hunt, you know; with the gun.
At first glance this doesn't look like an Atari game at all, if your drawing is true to the game.
Atari has more blob-like shapes in very bright colours.

I think I like the little border around the picture. It kinda -adds- something, but maybe it's just me that thinks that.
Cool ships, nice star field, is that a blue-winged bumble-bee?