Mega Man X is a series of action-platform games released by Capcom. It is a sub-series of the Mega Man franchise previously developed by the same group, with Keiji Inafune acting as one of the main staff members. The first game was released on 17 December 1993 in Japan on the Super Famicom and the following month on the Super NES in North America. Most of the sequels were ported to Microsoft Windows. The gameplay introduces new elements to the Mega Man franchise in the form of Mega Man's successor X, including his new skills and power-ups in the form of armors while retaining the ability to decide which boss to fight first. The franchise is also known for its replay value, in which certain choices and optional content can influence both gameplay and storylines, allowing the player to experience alternate scenarios.