Add hp bar to enemyes.
And just a sugestion at waves.
1st wave.
few weak
second
medium number weak
3rd wave
lots weak
4rd wave
few strong some weak
so on...
So, you need to add diffrent bullets for enevry weapons and diffrent shooting styles.
Also, i don't like that the ships sink really fast, they have no life bar and sometimes they are shaking which is sad. Add something named "story" to your game and have fun while making it. Good luck!
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