Since neuro-motor disorders have a primary relevance, rehabilitative therapies supported by medical devices are needed. The combination of serious games and IMUs is promising: this work focuses on a digital device allowing the patients to perform rehabilitation for upper limbs at home, for which integration of a functional calibration procedure to compensate the STS misalignment, a validation study, and a usability study were implemented. Results have revealed a general willingness to use the device and these findings will be used for the development of a new digital rehabilitation system.