Game--Avernum 2, An Epic Fantasy Role-Playing Game for the Macintosh

From Jeff Vogel, "Avernum is a prison. It is an enormous warren of tunnels and caverns, far below the surface of the world. You were banished there by the cruel Empire, to spend the rest of your life in the underworld. At first, it seemed like you and your many fellow prisoners might be able to form a nation and live in peace, far from the sun. Screenshots and a large, free demo can be found here."