The explosion effect is not smmooth :not enougth frames, we can see black outlines : it looks old school like old games.

Try using a shader, or use random particles , use effects on it , make it random, not the same looking each time.

Actually it looks like a simple bitmap with no lighting effect.

Juts a critic, take it as you want and not too seriously
(you are not a team of 20 or 100 people making the game :),
we know that and how much time it takes to make a simple game)