Objective: To develop and test the prototype of a serious digital game for improving community-dwelling older adults' heart failure (HF) knowledge and self-management behaviors. The serious game innovatively incorporates evidence-based HF guidelines with contemporary game technology. Materials and Methods: The study included three phases: development of the game prototype, its usability assessment, and evaluation of the game's functionality. Usability testing included researchers' usability assessment, followed by research personnel's observations of participants playing the game, and participants' completion of a usability survey. Next, in a pretest-post-test design, validated instruments-the Atlanta Heart Failure Knowledge Test and the Self Care for Heart Failure Index-were used to measure improvement in HF self-management knowledge and behaviors related to HF self-maintenance, self-management, and self-efficacy, respectively. A postgame survey assessed participants' perceptions of the game. Results: During usability testing, with seven participants, 100%, 100%, and 86% found the game easy to play, enjoyable, and helpful for learning about HF, respectively. In the subsequent functionality testing, with 19 participants, 89% found the game interesting, enjoyable, and easy to play. Playing the game resulted in a significant improvement in HF self-management knowledge, a nonsignificant improvement in self-reported behaviors related to HF self-maintenance, and no difference in HF self-efficacy scores. Participants with lower education level and age preferred games to any other medium for receiving information. Conclusion: It is feasible to develop a serious digital game that community-dwelling older adults with HF find both satisfying and acceptable and that can improve their self-management knowledge.