This paper presents a single-subject feasibility study of a motion-based VR game designed to provide benefits similar to constraint-induced movement therapy for children with cerebral palsy, while providing a more enjoyable experience. The game was designed to encourage the child to perform the desired therapeutic movements by allowing him to interact with the game using only his more-affected arm. The study used an AB design: Performance across baseline and intervention phases was assessed to determine whether the intervention resulted in changes to repeated measures. Results of the study showed that compared with baseline measurements done prior to his game experience, the participant's post-intervention performance showed improvement in speed of reach, dissociated movement, and bilateral integration of upper extremities in functional tasks. The child's mother, as well as one of his therapists, reported better performance outside of the study environment as well.