The idea is very interesting, spinning to recharge and planets as defensive towers, but it's pretty hard xD
The asteroids are easy enough but as soon as those bosses turn up third wave I just get destroyed immediately. I think the sun should have a good bit more of HP, or maybe even all planets, and the max charge for Mars should probably be a bit higher. Prices would also be a thing to consider, given how the sloar flare will destroy your first planets exactly before the boss arives