We kinda made the same game: Reverse Tower Defense with Goblin attackers. There were multiple others, so I made a collection.
Seems like we were both thinking about creative and dynamic ways for how to control the attacking units. I like how you went more into an RTS direction! My one critique was gonna be, that it feels a bit too easy, but I think the end of Level 3 feels pretty great, difficulty wise.
Very cool game! Great job!