"Play in the first RTS game with MMORPG like player progression in which you are rewarded every time you play. Every unit you kill in single player, multiplayer, or skirmish gives you experience points that allows you to level up your abilities and unlock new units, powers, and upgrades to your arsenal."

*cough* Worldshift *cough*

http://www.gamespot.com/pc/strategy/worldshift/index.html