Background: Despite current physical activity (PA) guidelines, children spend an average of 1-3 hours/day playing video games. Some video games offer physically active components as part of gameplay. We sought to determine if these active video games (AVGs) can elicit at least moderate PA in children, identify game elements important for PA, and determine if they are fun to play. Methods: Twenty children aged 8 to 16 years underwent cardiopulmonary exercise testing to determine their heart rate (HR) at ventilatory threshold. Participants played 2 different AVGs, and the gaming time that each participant's HR was above the HR thresholds for moderate and vigorous PA was determined. Gameplay elements that supported or inhibited active gameplay were also identified. Participants also completed questionnaires on physical activity, game engagement, and game experience. Results: The Dance Central Spotlight and Kung-Fu for Kinect AVGs produced at least moderate PA, for a mean of 54.3% ± 29.5% and 87.8% ± 21.8% of gameplay time, respectively. Full-body movements, player autonomy, and self-efficacy were observed to be important elements of good AVG design. Although participants enjoyed these AVGs, they still preferred their favorite games (game engagement score of 1.82 ± 0.67 vs 0.95 ± 0.70 [Dance Central Spotlight] and 1.39 ± 0.37 [Kung Fu for Kinect]). Conclusions: AVGs can provide at least moderate PA and are enjoyable to play, but most popular video games do not incorporate active components. The implementation of government policies and a rating system concerning PA in video games may help address the widespread sedentary lifestyle of children.