Really good game! I think with some more polish this could be a great standalone puzzle game.
With that said, there is a bit of a spike in diffuculty in level 12, there's just so many troops and robots to keep track of! Maybe it would help if a red line is shown after you aim a troop to show where it will shoot? That way it could be easier to keep track of which robots, boxes, etc. you haven't aimed at yet.
Still, good game!