Very Creative
You weren't lying about it being original. I thought this was very well done, though by level 13 I lost interest.
Thing to add:
i) Turrets. They could only fire straight out and would turn with your planet. You control when they shoot, but to make it fair, make them have a low fire rate.
ii) More asteroids, smaller buildings.
iii) DIFFERENT MUSIC TRACKS. The music you had playing made my ears bleed after the 10th loop. The settings was well done, but tracks with a tune would be nice XD
Well done. 8/10