This game reminds me a lot of Solar Jetman from way back in the NES days, and I loved that game!
I think it might play a bit nicer if drilling through the blocks was a smooth action, rather than a brief pause between each one.
The balance of finding the fuel crystals is good! It can get pretty tense at times watching the meter getting lower and lower, but you've got enough little clusters or single bits lying around to keep things running.
Some heavy mechanical noises would add a lot to the game, but am sure you've got enough stuff to worry about at the moment without that right now.
Am looking forward to seeing this keep developing