Nice tower defence
The gameplay was actually quite smooth, and there are some cool original ideas like the walls and the ability to relocate the towers. I don't agree that this is just another one. The fact that you have to guide the enemies along your defence, gives an extra challenge.
And that's also the problem. The beginning is confusing, as you have no idea about how the different enemies chose their path. There is also no way to influence the way the towers fire, which is a bit annoying in this setting. As mentioned by others, they inherently pick the first one, which makes them very inefficient at times.
Also the money gain is very slow. It would be nice if you could get a bonus if you call for the next wave before the timer runs out for example. As it is now, the game is pretty hard, and requires some devotion to get used to it. A bit more guidance or an easier mode to learn would be nice.