Eugen Systems is a French video game developer based in Paris, France. It was founded in January 2000 by the brothers Alexis Le Dressay, a DPLG architect, and Cedric Le Dressay, a software engineer. The company currently focuses on developing real-time strategy games for the PC and Macintosh platforms, but also has developed games for the PlayStation 3 and Xbox 360 in the past.

Act of War: Direct Action is a real-time strategy game developed by Eugen Systems and published by Atari. The game was released in March 2005 and features a detailed story written by Dale Brown, a retired captain of the United States Air Force and a bestselling author. An expansion pack called Act of War: High Treason was released in March 2006 in Europe and Australia, and in May 2006 in North America. The original game and expansion were later released as Act of War: Gold Edition, on 28 September 2007 in Europe. In September 2015 Eugen Systems released Act of Aggression which is considered a spiritual successor to Act of War.