I love the idea of shooting in space to kill enemies and propel yourself. Very good use of dual-mechanic design. 

I feel like the player could be given better feedback on the game state. It seemed like there was a large amount of variance between how quickly I would reload. Near the end of a level I got caught in a big mass of enemies and rather than be able to shoot my way out to make for a thrilling conclusion my gun wouldn't reload and I just kind of slowly cuddled to death.

I think your core mechanic is very good, it just needs level and enemy design and game polish to show its strengths.