A great game.
First off I've gotta say I really like the game and overall it was a very fun experience but one thing got on my nerves. I placed two slowing towers, later in one of my games, one on the left and another on the right. I tried the displacement upgrades, just to see what they were like, and thought they were pretty good until I got down to two lone enemies left that looped infinitely around my base and were continually knocked back by displacement. I had to sell one of the turrets to continue, wasting the money I'd put into it. While I understand that having turrets closer to my slowing towers could have solved the problem A slowing tower isn't too useful very close to the base, where my turrets are the most useful. Maybe I'm just being picky, and I don't really have any easy solution to fix that problem, but I do think something should be done.
Other than that, probably the best turret defense game I've ever played. Congratulations. :)