In May 2002, Sierra Entertainment announced that Mad Doc Software was developing ' as an expansion pack to Stainless Steel Studios' 2001 real-time strategy game "Empire Earth". Following an open beta test phase that started in August 2002, the game was released in September 2002. Mad Doc Software remained the principal developer of the "Empire Earth" series, and the next installment, "Empire Earth II", was announced in July 2004 and released in April 2005. Special praise was laid onto the game's in-depth interface, which allowed players to more easily navigate a game thought to be very complex. "Empire Earth II" was followed by an expansion, ', which was announced in October 2005 and released in February 2006. The final "Empire Earth" installment, "Empire Earth III", was announced in February 2007. With a total of spent for the game's production, "Empire Earth III" was released in November 2007. The game received overall negative reception and is considered to have terminated the franchise.