Citadel: Fortress Defense

A siege game played from inside the walls. Each day you build the town — walls, gates, farms, sawmills, quarries, towers, barracks, a mage tower — and then night comes and goblins, bandits and skeletons arrive to take it apart. You are the Lord, you can hire knights, archers and mages, and you can take direct control of any one of them in the fight, which is the part that separates this from a tower defense game: the wall you placed badly is a wall you then have to stand on.