There was some great stuff going on in your game. I really liked some of the puzzle mechanics you used, namely the ball, and advanced the difficulty well in the late-level by combining the previous skills the player learned through the level. Good level design.
The art style grew on me. Though I did find the main menu difficult to read or explore because it was harsh and maybe not the best style for information-seeking. I'd recommend more contrast when it comes to the UI.
Gameplay was fun and was tight and loose at the right places. The only thing that seemed inconsistent or was hard to get my bearings on was the use of the right mouse to arm my weapon and it shot inconsistently. That could be tighter or eliminated altogether. Just one click shoot.
Otherwise great submission. Nice job.