The objective of this study was to investigate the effect of serious games on hand muscle strength and functionality in a series of cases with ulnar nerve damage. Two patients were included in this 16-week intervention study using biofeedback. Electromyography electrodes and dynamometers were used in treatment. Functionality was assessed by Rosen and Lundborg score, Disabilities of the arm, shoulder and hand (DASH) questionnaire and International Classification of Functioning, Disability and Health (ICF). Grip and pinch strength were assessed by dynamometers. Results revealed an increase in sensory domain of Rosen and Lundborg score of the two patients. Patients increased values from the DASH questionnaire; however, they got better results with ICF. Grip strength of the two patients increased; pinch strength varied between patients; key pinch had the best results. Serious games can be effective to enhance hand strength and improve functionality in patients with ulnar nerve damage.