This is a really fun game! There are some serious issues that need addressing, though.
1. Game speed is seriously laggy.
2. Navigating is difficult due to the above-mentioned problem as well as the fact that the mouse controls seem to be on a hair trigger.
3. It's way hard to figure out from looking where a building can and can't go, as well as calculating bonuses.
Maybe using simpler graphics would help? Employing a shortcut to enable a top-down view would also be handy. Also adding some visual references to show the exact AOE cliffs and hills have.