Immersive Virtual Reality (iVR) Head-Mounted Display (HMD) systems paired with serious exercise games can positively augment the physical rehabilitation process from both engagement and analytics perspectives. This poster presents a serious game for iVR HMD based long term upper-extremity exercise. We demonstrate the capabilities of our game through a case study with five users recovering from upper-extremity injuries. We examine how our program maintains engagement and motivation over eight weeks, where users completed bi-weekly prescribed movements framed as protecting a virtual butterfly. We assess user experiences through a mixture of biomarkers from brainwave, heart rate, and galvanic skin response recorded at runtime as well as motion capture and behavioral game data. Our results suggest that the iVR game was an effective medium in inducing high compliance, physical performance, and biometric changes even with increasing difficulty beyond the novelty effect period.