Very well made game! Here is my honest review:
Pros
- Fun and simple to understand gameplay
- Nice SFX
- Various enemies and weapons
- Tutorial forces you to do actions (place hammer). By this tutorial becomes self-explanatory. That is pretty good
Cons
- When you play in 16:9 resolution, spaceships that appear from bottom start to shoot you offscreen before you can actually see them
- Meteors are hard to see. You should give them better contrast
- After mid game there is no point of money, because there is no place for weapons
My suggestions/improvements
- Add more places to place weapons
- Ability to remove/replace weapon
- It would be good to see shield that would block projectile and have it's cooldown. Or you can even make that you need to buy shield on button (for example on E), but it saves only from one hit. By this you will have more options where to spend money. You can add even more powerups that you can switch midgame
- Weapon and powerups (that I mentioned above) upgrade system
In overall I really liked your game. I hope you will continue to manage it further and release a full game. If you didn't understand something from what I have said, feel free to ask me.