Abstract-Distributed, real-time multiplayer computer games (MCGs) are in the vanguard of utilizing the networking possibilities. Although related research have been done in military simulations, virtual reality systems, and computer supported cooperative working, the suggested solutions diverge from the problems posed by MCGs. With this in mind, this paper provides a concise overview of four aspects affecting networking in MCGs. Firstly, networking resources (bandwidth, latency, and computational power) set the technical boundaries within which the MCG must operate. Secondly, distribution concepts encompass communication architectures (peer-to-peer, client/server, servernetwork), and both data and control architectures (centralized, distributed, replicated). Thirdly, scalability allows the MCG to adapt to the resource changes by parametrization. Finally, security aims at fighting back against cheating and vandalism, which are common in online gaming.

Although health game interventions seemingly enhance the physical activity self-efficacy of children and have potential as a means of increasing physical activity, more rigorous research is needed to clarify how effective such interventions are in the longer run to contribute to the development of game-based interventions.

Effective, evidence-based, and interesting methods are needed for children's health promotion. Digital games can be such a method, but there is need for a summary of the evidence on the effectiveness of digital games in promoting children's health. The aim of this review of reviews was to evaluate the quality of systematic reviews, to summarize the evidence in systematic reviews and reviews related to the effectiveness of digital games in children's health promotion, and to identify gaps in knowledge. A systematic literature search was conducted in May-August 2013 from relevant databases, and 1178 references were found. In total, 15 systematic reviews and reviews met the inclusion criteria. Most of the systematic reviews were found to be medium quality on the AMSTAR checklist. Most commonly, systematic reviews and reviews evaluated active videogames. According to the results, evidence of the highest level and quality seems to support an increase in physical activity to light to moderate levels and energy expenditure, especially when playing active videogames that require both upper and lower body movements. In addition, sedentary games were shown to have potential in children's health education, especially in supporting changes in asthma- and diabetes-related behavior and in dietary habits. However, there are still several gaps in the knowledge. There is a need for further high-quality systematic reviews and research in the field of health games.

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In the present study, we validated Gameplay Activity Inventory (GAIN), a short and psychometrically sound instrument for measuring players' gameplay preferences and modeling player profiles. In Study 1, participants in Finland (N = 879) responded to a 52-item version of GAIN. An exploratory factor analysis was used to identify five latent factors of gameplay activity appreciation: Aggression, Management, Exploration, Coordination, and Caretaking. In Study 2, respondents in Canada (N = 1322) and Japan (N = 1178) responded to GAIN, and the factor structure of a 15-item version was examined using a Confirmatory Factor Analysis. The results showed that the short version of GAIN has good construct validity, convergent validity, and discriminant validity in Japan and in Canada. We demonstrated the usefulness of GAIN by conducting a cluster analysis to identify player types that differ in both demographics and game choice. GAIN can be used in research as a tool for investigating player profiles. Game companies, publishers and analysts can utilize GAIN in player-centric game development and targeted marketing and in generating personalized game recommendations.