Armored Core 4 is the 12th installment in the Armored Core series. The games are set in an alternate universe where corporations fight wars and have taken over governmental control. Due to the growth of the population, food and energy became scarce and widened the gap between the rich and the poor. Anarchy ensued and the government lost control of the situation. People turned to the corporations to provide for safety.
Five years after the establishment of a new order, the player takes on the role of a rebel fighting against the corporations. The player controls a giant Mech, part of a squad, which can be assembled and customized with various parts, weapons, and aesthetic options. The goal is to challenge the modern slavery system by force. On different locations around the world, the player fights Mechs from the corporations in 30 missions grouped together in chapters.
As the player progresses through the game, new parts become available for customization, and the Mech can be repaired with wages earned at the end of each level. The game also features multiplayer support over the PlayStation Network and Xbox Live.