Dear Prof. Boulos, Thank you for your reply. Yes for general applications I agree with you that the social component is very engaging, but what are your thoughts when it comes to m-health applications? Also, the user behavior and expectations in m-health applications are a bit different that the general applications I believe, your thoughts on this please?
I indeed had mHealth applications in mind when I wrote the above answer. Games are often bundled with a social component (e.g., multiplayer mode, leaderboard, etc.), but you can also have a powerful standalone social element outside conventional gaming contexts. PatientsLikeMe is a perfect example of an mHealth app featuring peer-to-peer (or call it 'patient-patient') support and disease-specific online communities: https://play.google.com/store/apps/details?id=com.patientslikeme.android
PubMed has many research papers about PatientsLikeMe.
Gamification, as you mentioned, is not one technique it is more about "learning from games" what makes them so engaging and motivating, using not only simple elements but "game-design elements in a non-game context" [1], meaning also mechanics, aesthetics and processes [2].
Motivation (and engagement) itself has it's theories. For example self-determination theory. There are theories focussing on the individuals needs, physical or psychological (content theories, e.g. [3]) and there are theories focussing on cognitive processes.
All of those approaches can be used to determine how to improve the usability of a system (and improve the user motivation) and to fit the users needs and requirements. To improve the user-motivation, it is key to understand the context of use, to analyse precisely what it is that motivates the user as an individual to enhance the correct motivational elements. Theories (gamification, psychology, motivation...) can be used to backup ideas and hypotheses for design decisions and can help us understand the underlying concepts of motivation and engagement. In the end, what motivates a user is determined by the users situation and context.
[1] Deterding, S., Dixon, D., Khaled, R., & Nacke, L. (2011, September). From game design elements to gamefulness: defining gamification. In Proceedings of the 15th international academic MindTrek conference: Envisioning future media environments (pp. 9-15). ACM.
[2] Hunicke, R., LeBlanc, M., & Zubek, R. (2004, July). MDA: A formal approach to game design and game research. In Proceedings of the AAAI Workshop on Challenges in Game AI(Vol. 4, No. 1, pp. 1-5). AAAI Press San Jose, CA.
[3] Maslow, A., & Lewis, K. J. (1987). Maslow's hierarchy of needs. Salenger Incorporated, 14, 987.