Really like the sound track ! and use of colours
Could I throw to two cents in, and suggest that it needs another type of alien ship that moves across the screen
in a different formation to the attack waves, and these aliens would shot photo torpedo's (missiles) at you
Maybe also a mother ship every now and then otherwise, your just blasting wave after wave of similar attack formation,
the addition of a second type of attacking ship, shooting back at you would make it impossible to just sit in one
spot and blast at the formation.
even some ground based cannons firing at you would be cool
some power-up's to increase the fire power ?
Not trying to knock it, excellent game design
could listen to the sound track for ages, while blasting those
nasty aliens into the next world