Neat graphics and gameplay! Overall, the gameplay was really well polished and well-rounded. Being a top-down shooter I would say it can be relatively boring once you've played for a bit since it doesn't deviate much from a standard top-down shooter and feels quite similar to other games.
A few nit-picky things I think would really make the game feel more exciting to play would be:
- Screen Shake - always good to have in any action game
- Faster enemy spawning - helps keep the pace of the game up
- BIGGER bullets (lol) - its weird but larger faster bullets usually work really well for arcade-style games
- And of course some form of unique idea or mechanic that separates it from other games would be fantastic if you wanted to work on it anymore
Overall very polished, a neat cast of enemies, Great Job :D