Stroke is a medical condition that can leave a person physically and cognitively impaired. It is possible to regain the lost functionality through repetitive exercises that help in retraining the brain. Post-stroke rehabilitation can extend from months to years, and it demands motivation and a disciplined exercise routine to achieve the recovery goals. Games have been used to transform these repetitive exercises into fun engaging activities during therapy. This project is focused on the use of smartphones for delivering exercise routines in a low-cost and accessible manner. We present the design of an exercise game for finger dexterity that can be played by stroke patients on a smartphone as an adjunct to treatment, alongside visits to the therapist. Apart from converting finger exercises into game controls, the design of the game also helps patients maintain an exercise routine as well as motivates them to take charge of their recovery pace. The primary game mechanic was prototyped and evaluated for its feasibility by an expert therapist. The feedback received was used to develop the game further. The final design has been presented in this report.