First of all, thanks for doing "hold mouse button to shoot". So many shooting games in this jam had me forced to spam click the left mouse button.
That being said, i'm not a fan of the fuel mechanic. I was honestly overwhelmed most of the time and I could just shoot fireballs.
I didn't have breaks to build "towers". I had no indication on where the enemies are coming from. The crown and fuel are glowing brightly, and there is too many visual effects so I don't see enemies often before it's too late.
I can see a lot of effort has been put into this game, and I do value it so I am rating it highly. I just think some deviations you decided to take from the tower defense genre didn't land quite well in this game.