This is a really cool game. First I love the art, it's really well done and the limited use of colors is just really nice to look at. The animations for the player, the jelly fish and the shoot are also super smooth. The SFX is also well done and the overall concept and implementation of the theme is simple and nice. Movement and camera movement also feels super polished to play with.
Here are some few critiques I have:
I think this game will heavily benefit from some sort of tutorial as I didn't know the button R refilled my charges.
Sometimes the enemies spawned right one me which ended the run, I think there should be a safe zone around the player where the enemy can't spawn.
In the future I can definitely see this expanded upon being a roguelike where you get upgrades after each wave and variety of enemy types while you try to defend your tower.
Overall this is a great game jam entry, good job :D