The GENERALS series puts players in command of one of three world powers: the US, China, or the GLA terrorist group. Zero Hour introduces nine subfactions, units under one of the three powers, including the US air force and the Chinese infantry. Each has its own unique leader and its own playing style. Some subfactions may not be able to build every unit available to its umbrella faction but may have access to specialized technology that no other group has. In the new Generals Challenge mode, a player's subfaction is pitted against the other eight on their home territory. The game also includes five new missions for each of the three superpowers.