I had a hard time playing this, probably because I suck.
I had no gun, that made me sad. When I went to the upgrade screen I kept trying to read what the upgrades did and in that time I would be ambushed and killed. I found that my engines dealt damage and was happy, but had a hard time getting close to the enemies to kill them with my engines. I tried running them through the asteroids, and it helped, but I still couldn't figure out what upgrades to get because I kept dying when reading the upgrades.
I think it would be more fun if you carried over your points you earned, that way you earn something for each life. Perhaps, you have to return the goods to the base, then they're saved. Then enter the upgrade screen and it pauses.
These are just some ideas, but I won't dock you points because I suck.