This is absolutely addicting to play! I had to really pull myself away from the keyboard to stop playing! I really love how every building is pretty minimal in design.
The only thing I would suggest is to have some kind of tooltip or some kind of description somewhere as to what each building does, and what each color means in the inventory. I was able to figure most of it out in the end but It'd be nice if I didn't have to. UNLESS of course that's what your going for.
Loved it, will be back to play more!!