I’m working with NinjaNic to make this more of an actual village builder than a tower defense game. I replaced towers with house. Each house slowly expands until it has eighteen people living it, and each person in the house contributes one gold (so if you have a house that has ten people in it, you will incrementally get ten gold). Instead of you manually changing the look of the houses (as NinjaNic suggested), I opted for a Caesar 3-like system where they change over time; in this case, depending on occupancy. At ten people it will changes its look; and at eighteen people, it will changes its look one more time.