Looks like a great game. I would recommend some changes to make it less frustrating:
- bats don't instantly home in on you, but instead stand still for 1 (maybe 2) seconds and then come after you. This gives you some time to react to them when they're right on the other side of the wall you just destroyed.
- be able to heal up when going back into your ship
- make it impossible to spawn falling rocks on top of you, especially if you stand still. Might not be as frustrating if you're able to heal up in some other way then dieing.