No other physical retail versions of the game will be available. (ticgn.com)
Mighty No. 9 will be available on 15th September 2015 in the Americas and on 18th September 2015 worldwide as a digital download as well as physical retail version for Xbox One, PlayStation 4, Wii U, PC, Linux and Mac as well as digital only on the Xbox 360 and PlayStation 3. (playstationing.com)
According to a post on the PlayStation Blog, the game will include both digital and physical retail versions when it's released and will offer more than 30 songs. (seganerds.com)