Traditional methods of cognitive assessment using neuropsychological tests are expensive and time consuming. These methods do not lend themselves to frequent monitoring and trend detection. In this paper, we describe a method for using enjoyable computer games with embedded cognitive metrics to monitor within-subject trends in performance. We have created a set of 9 computer games to specifically measure various cognitive domains that are normally administered in routine neuropsychological assessments, such as verbal fluency, working memory, attention, and planning. Although the measurements are not taken in a controlled setting, there are distinct advantages to being able to collect data frequently in a naturalistic setting. Routine measurements over time allow us to detect trends in various aspects of cognitive performance and avoid biases due to education, culture, and experience.