Gamification is widely used in various domains as it helps increase user motivation and engagement. Therefore, it is important to ensure that the gamified system meets usability requirements and conforms to user experience and human-centred design guidelines, as poor usability may lead to undesired side-effects, such as a loss of user retention. Unfortunately, it is not entirely clear what usability guidelines are related to gamified systems and how they depend on the gamification target audience and on the gamified system application domain. This paper provides a systematic review of usability, user experience and human-centred design guidelines for gamified systems. A systematic search was performed in Web of Science, Scopus, IEEE Xplore, ScienceDirect, and ACM Digital Library databases, following the PRISMA guidelines. The results show that most of the recommendations listed in analysed papers are related to improving learnability of gamified systems. Furthermore, the system application domain is generally viewed as very important when making usability-related decisions. The key distinctive gamification application domains are medicine, education, and business. The findings may be useful to usability and gamification researchers, as well as the developers and owners of gamified systems who want to grasp the state of research into the specifics of gamified systems usability.

Gamified systems combine information system functionality with gamification elements to support motivation and engagement. However, existing gamified system development approaches lack a unified method to identify usability recommendations for both the system as a whole and individual gamification elements. This paper proposes MIURGS, a method for identifying usability recommendations for gamified systems according to user and system characteristics, including age group, application domain, gamification goals, usability goals, and principles. The method is implemented in a dedicated tool and supported by a knowledge base containing usability recommendations and gamification element suitability recommendations. MIURGS was evaluated through two studies: a student experimental evaluation with 45 participants and an expert evaluation with 12 respondents. Results of the student experimental evaluation indicate that for general recommendations, identification, gamification element selection, and ease of identification, tool-supported process results were better evaluated than unaided identification. The expert evaluation further indicated that the method is perceived as useful and relevant, with 11 of the 12 respondents agreeing that it would reduce the effort required to identify usability recommendations.