I've been enjoying the demo of both versions. I think there could be some improvements to the controls to make it a bit more user friendly. I say this as a professional UX designer with 15 years experience.
B traditionally is back or cancel rather than select so I would rework the controls so A is select and B is cancel, I would also change it so you press A to select a tower and that then has options to upgrade or sell it, rather than having separate buttons