to overcome to balance the gameplay. In 2006, Chris Rubyor, a former employee of Westwood Studios, discussed the galactic conquest mode of the game, stating that the initial mode had to be overhauled several times because Petroglyph was unhappy with the original mode. Rubyor said the game's skirmish mode incorporated a variety of new and traditional strategy mechanics found throughout RTS genre. He also said the game's focus was primarily combat and unit tactics, while allowing units and new technologies to be purchased during skirmish combat, a feature that was not put in the main single-player campaign or galactic conquest. The game's musical score was composed by Frank Klepacki. Klepacki said surround sound was an important aspect for the game because he said he believed many past RTS games did not take advantage of the features of surround sound. The game's audio took elements from the Star Wars films, as well as adding new elements to add variety to the game. Much of the sound effects were created by Klepacki, including all sounds in the interface and structure. A stage demo and trailer were on display at E3 2005. On July 15, 2005 LucasArts released a new trailer and announced a release date of February 7, 2006. A playable build of Star Wars: Empire at War was well received at the 2005 Games Convention in Leipzig, Germany. The official demo of Star Wars: Empire at War was available for download on January 18, 2006, for Microsoft Windows systems. It featured five introduction tutorials to the game, and one galactic conquest mission with the player assuming the role of the Rebel Alliance. The full Windows version was released on February 16. On November 3, 2006, Aspyr Media Inc. announced Empire at War would be coming to the Mac OS X platform in April 2007. The Mac demo was released in March 2007. Reception Star Wars: Empire at War received a "Silver" sales award from the Entertainment and Leisure Software Publishers Association (ELSPA), indicating sales of at least 100,000 copies in the United Kingdom. Star Wars: Empire at War received "generally favorable reviews" according to the review aggregation website Metacritic. GameSpot said, "Empire at War delivers a true Star Wars experience". IGN said, "Star Wars: Empire at War definitely scores big in terms of style.... If you're hoping to enjoy this game because you really like Star Wars, you'll probably be satisfied