It's a great concept, and controlling the RC car was fun. One change I would make are to attach a lens flare to the car and robots, and have the flares exclude all layers. This way, you can see where they are even when they're under the treehouse. Another way to do this would be to put a little icon on them, and have a second camera render these icons when the first one is finished. (Settings in Unity for the camera: "Don't clear", depth > the first camera, and only renders the layer the sprites are on).

Again, it's unique and fits the theme really well. Keep working on it.

Super idea. Even though I wasn't able to protect my garden, the concept looks promising.

Nice concept :). The models are really good :D. At the beginning it was a little difficult for me to control the car, but after some practice I got better. It gets a little complicated when the car gets under the treehouse, because you cannot see it. This could be a nice game if you keep working on it :)