From Wikipedia:
Civilization II: Fantastic Worlds added new scenarios that had many unique settings such as one scenario dealing with colonization of Mars, one scenario called Midgard that had Elven, Goblin, Merman, and other civilizations from fantasy. There was also some scenarios based on other Microprose games such as X-Com and Master of Orion scenarios. Fantastic Worlds also created a whole new scenario editor that allowed changing units, city improvements, terrain, technology trees, placing triggers, and vastly enhancing the game.