Dark Reign narrowly beat Total Annihilation as the first RTS to incorporate 3D movement and positioning. This increases the strategic advantage of hills and mountains.
Each mission puts you in the role of the commander of either the Imperial army or the Freedom fighters in a campaign to undermine and eventually destroy the opposing force.
This game has many unusual features for the RTS genre. AI patterns allow you to simply give a unit the order "Search and Destroy" and it will drive off towards the enemy's last known location, in search for something to kill. There is also an "explore" mode which lets your units do all the map exploration for you. A mission/campaign editor is also provided.
Dark Reign.ws - Home of Dark Reign! (Excellent site dedicated to the game and its expansion pack. Also offers patches, maps, mods, new units, you name it. They've got a server running for multi-player games and there's an active community forum.)
Zhentarim7 (197) added Dark Reign: The Future of War (Windows) on May 30, 2000