Hey, thanks for the feedback, glad you enjoyed the game! Yes, a better tutorial/explanation of how to play was on my mind at the time of making the game. I was running out of time and decided to just slap on some text that kind of explained the point of the game and what the controls were. Definitely, something that I wish I could have added.
Tower Upgrades were also another thing on my mind that I couldn't achieve due to not having enough time. It's something that I want to add to the game moving forward.
As for the elemental battery, there's definitely room for improvement, and I'll be taking everyone's ideas into consideration. Thanks so much for the nice comment, I hope you had fun playing it :)