This was a LOT of fun, the art is great, and (once I got the hang of it) watching the astroids get annihilated felt really rewarding.
I only really have two complaints...
One: I didn't understand how to play at first, (but after I got the hang of it, it was really fun) I didn't realize the thing in the top was my health, I thought it was some sort of timer, and I still don't know how getting more gears work, but that didn't really stop me from playing it. I also didn't realize that to many trees would kill me, which kind of makes since, being that humans can't survive if there is to much oxygen, but still.
Two: At a certaint point the game just kind of goes on, and you can't lose. After you have enough drones in the sky, the game just can't end, the astroids can never get to you, in my second playthrough I was able to set up the world in time and last infinatly. I was just able to phase out for 10 or more minutes after getting to that point, and let it run, without having any challange at all. I would suggest either having some sort of win condition, or making so mechanic to increase danger, where you will always eventually lose, rather than just sitting their watching the planet doing nothing.
Now, other than that, this game was a lot of fun, I just feel like some sort of ending would have been nice, some sort of closure rather than me just turning it off after realising it wasn't going to end.