Exergames offer exciting perspectives not only for rec- reational, but also for therapeutic use. Increasing num- bers of older adults in many industrialized countries raise the need for affordable and reliable solutions to help people to stay healthy and fit at advanced ages. While games user research is vital to increasing the quality of game designs and improving game design processes, many research tools are difficult to use with senior gamers, and the target group is especially vul- nerable to mistakes both in game design and games user research. We report and classify some of these challenges along with possible approaches, aiming to fuel intensified ex- change about methodological experiences among re- searchers in the field.