I just played this for a couple of hours. I got the huge creature (boss?) to spawn, but I could not beat it. The strategy I found best was walls as a last line of defense on the left, laser towers in the middle, three air-towsers in the middle was well, and some grinders where the enemies spawn (but I'm nor sure if they are really worth it).
Is it possible to beat right now? What's strategy that works?
Looking forward to playing a more complete version, this looks really, really good! Contratulations!