Ghost Master: The Gravenville Chronicles

By scaring humans, you collect plasm, the main resource in the game. Plasm can be used to recruit new ghosts, or expand their abilities. Rather than deploying a massive amount of creatures, the game rewards creative use of limited resources to haunt mortals in original ways. Each human has a believe meter. An important aspect is figuring out each human's weakness. As you exploit this, they become more susceptible to various phenomena and provide more plasm. Along the way, you will meet fierce resistance as ghostbreakers, priests and witches can detect and ban your ghosts.