Dungeon Keeper (1997) is available for free on GOG.com for two days. It's a very unique classic strategy game in which you play as an evil overlord, and must build a dungeon, filled with various monsters and demons to defeat invading heroes. Well worth checking out, it's a lot of fun and includes the "Deeper Dungeons" expansion pack too.
If you're interested in giving it a try, it's right on the front page of http://www.gog.com
If you're interested in giving it a try, it's right on the front page of http://www.gog.com