The Elves are a selectable faction at the start of the game if you have Return of the Elves installed. Elves have powerful but expensive units and are good at maximizing research production. As living beings, they require food to grow cities.
Elves have access to the following special buildings:
Transmutation Facility (Built on Iron deposit), the Design Department (built on Neveril), and the Rectification Facility (built on Adamantium).