Wow, this game looks amazing! I particularly love the enemy model
In terms of gameplay, it starts out fun, but it's clear there needs to be some balance changes. You can easily make an impassable wall of turrets since the enemies don't ever increase in health. Unfortunately, it's optimal to ignore the color-changing mechanic; a 2x damage increase doesn't mean much when you hit 1/3 of the enemies.
Great work, I think this game has a lot of potential!