i like it because its original, has nice simple controls, and it has alot of room to become something so much better
but i feel like this is a pre-release to something better, as if you were simply seeing if people liked the concept before moving onto a full game,
the upgrades were deefinitely lacking.
and it got boring after about level 10.
but, i think that if you made another version of this, with maybe more upgrades and stuff,
like maybe some levels could have asteroid fields, with moving rocks, and when the meteors hit the field, they would scatter, possibly blocking the meteor, or possibly sending space debris into your planet. thus helping or hurting the player.
maybe space ships that fly in and hover above the surface annoying you with lazers from time to time...
just these are just things to think about.
aside from the music, i liked it, moderate scores from me for a really good idea.