Overall a super fun game. I loved the slow power crawl of being able to build a small army behind me. The graphics were good, the flashing enemies when hit was a nice touch. Unlocking new units felt natural and overall I think the game was great.
If you wanted to improve, I suggest having some sort of indicator on enemies if they are or have been successfully targeted, maybe make them flash or glow red. Also, if the player is attacking and the followers have no target, they should automatically start attacking.
Overall a super fun game. I really enjoyed it!