Exergames are increasingly considered as an exercise instruction modality in health applications. Studies are typically conducted in non-situated contexts and capture short-term effects. We present first results from a medium-scale study conducted over the course of 5 weeks and integrated into a normal rehabilitation program. The study features three groups, comparing manually adjustable exergames with the identical games in adaptive versions and manual physiotherapy interventions without games. The results indicate that the exergames and traditional therapy are comparable regarding measures of competence and enjoyment, while exergames led to significantly higher scores for autonomy, presence, and in a functional reach test. With traditional therapy, scores for tension-pressure and effort-importance were significantly higher. The initial results of the broader study presented in this paper deliver insights regarding motivational aspects of exergames and traditional therapy and point out which motivational aspects could be strengthened in future implementations.