Super cool idea. You started with the same game idea of changing up a tower defense game as I did, but created a completely different game and I really enjoyed it.
The tower controlling mechanic really feels nice, but is slightly hindered by not greatly indicating which towers are currently selected. I also needed some time to understand that I could select multiple towers at once. But both of these things are minor problems.
Such a great game with a lot of potential. Keep it up!