This paper describes research and development around two gameful courses that reimagined their assessment systems to better support student autonomy and promote engagement. We present results from an ongoing classroom-based research study that signals the success of these designs and, in so doing, explore key elements of what we call gameful design: the process of redesigning core elements of a learning environment to better support intrinsic motivation. We describe this process and discuss a set of promising practices for the design of gameful courses. Results from three studies indicate that gameful course design is positively related to students working harder and feeling more in control of their class performance.