This paper introduces WiiPD, an approach to home-based objective assessment of Parkinson's disease. WiiPD aims to make use of the many capabilities of the Nintendo Wii Remote in combination with a number of bespoke data gathering methods to provide a rich and engaging user experience that can capture a wide range of motor and non-motor metrics. In this paper we discuss the architecture of the approach, and provide details of the implementation and testing of the motor-assessment component of the system. Initial results of testing on 6 users indicate that the system is able to differentiate between normal and abnormal motor performance, suggesting that the system has the potential to monitor the motor fluctuations associated with Parkinson's disease.