I actually prefer this one of it's predecessor, chapter 0. When I think tower defence I don't think difficulty, or puzzle. I think fun. This game is just that, fun. However I think TD games do need some strategy, and again this has that.
I really don't like this pong thing... at first it looked like it might be a decent puzzle game, but then it added some strange skill based things, and it really didn't help it much. 2/5
Also I beat the boss with leecher, and if you don't know how to get it, it goes as follows: fighter 1>fighter 2> fighter 3> fighter 4> leecher. At that stage you can also get super fighter, or ghost sniper. You can go Heavy 1> Heavy 2> Heavy 3> Heavy 4> dronet tank, super heavy, or Bft carrier.