I really like the concept, it feels like a fresh new take on tower defense, where you are trying to protect yourself instead of something else ! A small touch that I liked, was the fact that towers attack the enemy that is the closest to you, which gives a nice layer of strategy to the player's movement.
I think making the enemies a bit more interactable would have made the game even better, for instance, when you are surrounded, there is not much you can do. I would have liked if, for example, you could throw a battery at an enemy to push it away, to give you a small opening to escape.
Cool game !