Very cool game. The gameplay loop of rushing back and forth trying to pick stuff up/place buildings before enemies showed up was fun. I did feel like the start was a little slow, with mining and carrying one rock to the station at a time.
I kept running into issues with hit detection, I would fly through tiles with cheese without picking it up and could not get through the bounce pad level without passing through one and flying into the void.
This is really cool, I've never seen a Space Invaders/Galaga/Galaxian type shooter with this kind of theme. The enemies only shooting straight forwards and not moving much does make it easy to cheese them if you clear out a small area.
Fun game, I kept overshooting the top of the box and waiting to see if I would come back down or not. I was surprised to find out that you could land as fast as you wanted without crashing.