The game was originally scheduled for release this spring, but developer Comcept's recently established partnership with publisher Deep Silver proplelled the rescheduling of the release date. This makes way for more features to be added to the game.
Additionally, the DLC set consisting of an additional stage with an extra boss and a new playable character named Ray will be made available in the physical versions of the game, and the pack will be free for all the backers.
Highly touted as the spiritual successor to Keiji Inafune's earlier brainchild--the classic Capcom platformer series Rockman--Mighty No. 9 will be released for virtually all the exsting platforms to date: the PlayStation 3, PlayStation 4, PlayStation Vita, Nintendo WiiU, Nintendo 3DS, Xbox 360, Xbox One, Windows, Linux and OS X. It will be available on September 15 in the US and on September 18 in other parts of the world.
Source: MightyNo9.com