Alamo Game Engine is a game engine developed by Petroglyph, which is used to create the real-time strategy games Star Wars: Empire at War, and Star Wars: Empire at War: Forces of Corruption. A modified version of the Alamo Game Engine was used for Petroglyph's third title, Universe at War: Earth Assault.
One of the best RTS engines out there, on par with EA's Command and Conquer engines.