Good concept, still needs tweaking
First off, there are way too many commands assigned to your left click. If every control in your comments section has the option of using your click/double click to activate, that's too many. Yes there are other keys that operate functions, but the fact that the left click can operate everything is a problem because one could easily be meaning to do one action while using the left click and inadvertently key an undesired one. 99% of people have keyboards, I would suggest removing at least some action commands from the left click and assigning them to keys.
Another issue is the difficulty, which is tied into your energy concept. I like it, but it also needs some tweaking. Easy plays like medium, and medium like hard. Either reduce the energy drain of movement/boost/shooting, or give better rewards. Since shooting a laser should be more taxing on energy, movement/melee tactics should be emphasized. I'll also accept movement costing energy, but after you break atmosphere and gravity in level 1 it should be reduced, and realistically cost no energy if you aren't moving at all in space.
Bugs still need to be addressed. I specifically encountered one near the end of level 1 where it nearly was over, the missile wasn't off screen but near top, I ran out of energy but I didn't end the level in failure.
Needs work. Since you say in comments that this is version 1.2 I can only assume you do check the game and improve it. Hope this helps you and other players.