Thanks for the game!
This was a quite tragic experience for me since I kept failing to protect the pylons from exponentially growing numbers of enemies. The music and surroundings were quite serene, and the turtle's face smiled at me when I managed to look into it. I felt quite powerful with my magic rainbow lightning and water spraying rod, but this power was not enough to protect crystals from hordes of flying drones and mechanical spiders. I was also somewhat confused at why my water spray cannot cool down overheated crystals, but then I realized, by looking closely at the magnificent orange flare, surrounding them, that their heat was of some other, immaterial nature and could not be diminished with water. I kept returning to the Turtle island over and over again in the vain hope of saving it from invaders, but with each new attempt, my failure was more and more humiliating (seriously, though, even after losing the game and restarting it over again the number of enemies in each wave did not reset for me, so I think it was a bug).
The gameplay idea is very simple and effective, and the visual execution is of the highest quality! Your game reminded me of some of the older third-person action games (like Sacrifice, for example). It's definitely somewhat clunky in terms of controls and collisions, but that is to be expected from the full 3D action game made in 3 days (saying this from personal experience). But the bright and cheerful tone of the game contrasted so deeply to me with it's pressing difficulty that I couldn't help but think that this was not intended on your side.