I had a lot of fun playing this game! The music is really fitting and I love the cinematic finish when defeating the boss. I really like how the boss moves side to side mixed with the graphics style it reminds me of space invaders.
My one piece of criticism I think is I wish you could build more than one structure per planet. Since each planet is capped to one, I feel like I'd always rather build a laser or a factory on them.
Awesome job and great take on the theme!