What a great, great idea! At first, I was like "wtf is this, this doesn't belong to the jam, where is the theme?" and then you got me hard xD.
The concept is amazing, and the more I played, the more I learned about the mechanics and subtilities of the game, it felt amazing. The planning of my first and my last games where COMPLETELY different and went through a lot of iterations because of all the little things I learned. The fact that turret have unlimited range, but friendly fire, the fact that you cannot just hide behind debris, the fact that hearts stay between runs... All these little mecanics create DEPTH to your game, and heavily influence your thinking. Playing felt good and rewarding. Something that felt a bit unfair sometimes was that turret seemed to shoot on whoever the wanted. Usually, on TD games, the turrets always go for the enemy that is the furthest on the path, but here, I don't really know, and they sometimes tried to shoot an enemy behind another tower instead of somebody that is going to reach the end ^^'. But that's just a nitpick, the game design is awesome ^^
The graphics are really cute and I loved the little details like the particles when you place a path. The visuals are clear and pleasing without feeling overwhelming whene there are a lot of enemies on screen.
The sound is nice ^^. Every action have a sound, and the music is enjoyable. I would have really enjoyed of the music changed during the swap, tu put more emphasis on the change, but overall, the sound design if nicely done!
So overall... That's a great game! A cool concept with a nice execution! Congratulations =)