Great, few tweaks needed
This is a great TD type game with lots to keep you re-playing (tech tree combinations). Only annoyance is that it appears not to support native MacBook Pro retina resolutions.
The camera is also a bit poor in that you don't appear to be able to rotate it at all (even if it was locked in the overhead view, rotation would still be useful). This is particularly annoying when trying to deploy towers behind buildings/hills.
Overall though, great for the price and a welcome interruption to work :)