Critics have credited "Age of Empires" for influencing real-time strategy (RTS) games such as "Rise of Nations", "Empire Earth", and '. ' was also influenced by the series: it utilized the Genie game engine, as "Age of Empires" and "Age of Empires II: The Age of Kings" had, and was considered by critics to be a very close replica to the games; IGN began their review with the statement "I love "Age of Star Wars", I mean "Star Empires". Whatever it's called, I dig it." and GameSpot wrote that "fundamentals of the "Age of Empires II" engine are so intact in "Star Wars: Galactic Battlegrounds" that veterans of that game can jump right in." In October 2005, Shelley commented on the impact of the series. In a GameSpy interview, he explained that parents would "tell Ensemble Studios that their kid is reading books about ancient Greece because they enjoy playing with the triremes so much, or that they want to check out books about medieval history because game taught them what a trebuchet was."