# Towards High Usability in Gamified Systems: A Systematic Review of Key Concepts and Approaches
## 4 Discussion  
The results of the review presented above served as the input answering the research questions RQ1-RQ3. The key observations are presented below. RQ1. What is the nature of specific usability recommendations for the gamified systems? The authors of the selected papers positioned their findings not only as usability recommendations, but also as recommendations for building better, more serious games, ensuring a better user experience, higher motivation or engagement and better compliance with human/user-centred design principles. Despite that, many of the 259 identified guidelines and recommendations addressed the same issues and therefore a summarised list from all of the 20 papers included just 30 items, 7 of which were dismissed as not relevant to this analysis. In terms of the nature of the recommendations, the variety was good, with all ten Nielsen heuristics and all six ISO 25010 usability characteristics, that were used to group recommendations, covered. The usability characteristic that was addressed the most was learnability, while the user interface aesthetics aspect turned out to be the least important for the gamified systems researchers. The examples of generalised recommendations aimed at improving the learnability of gamified systems were R2-provide feedback, R3-use familiar vocabulary, R4-ensure that available actions are relevant to goals, R5-use modality principle,  
Figure 7: The number of recommendations (before merging similar ones) with respect to gamified system target audience, application domain and the nature of the recommendations provided in the publication. R6-provide help to users, R7-ensure onboarding, R8-use information segmentation, R11-ensure consistency of elements, R13-provide clear error and warning messages, R14-provide challenges that grow with user skills and R28-ensure easy navigation. As can be seen from the list above, many of the recommendations were what one could classify as universally accepted, e.g., using familiar vocabulary, providing good feedback, error prevention, information segmentation, ensuring short response times, etc. On the other hand, the authors often recommended using modality and signalling principles as well as ensuring onboarding (relevant information before the task) and providing fatigue management features (adaptable time limitations and speed of work). Such guidelines are not applicable to all software systems, but clearly should be taken into consideration when developing gamified ones. Overall, all ten of [PERSON]'s heuristics were covered by the analysed authors in their recommendations, led by N5-error prevention (38 individual recommendations) with N4-consistency and standards coming last (12 individual recommendations). Most of the recommendations provided in the selected papers were of a general nature, and concrete instructions that could be used by gamification software designers and developers were relatively rare. RQ2. Do gamified system usability recommendations depend on the gamification target audience? The majority of the selected papers addressed the usability of gamified systems aimed specifically at either children or adults (30% and 30%, respectively) indicating that age is an important factor when making the decision on how to build or improve gamified systems. Out of six papers presenting adults-oriented recommendations, half were aiming specifically at the elderly gamification audience. The authors of the remaining 40% of the selected publications did not specify any characteristics of the gamification target audience for whom they were providing recommendations. Other user characteristics that typically influence usability-related system development decisions, such as user goals, level of motivation, education or IT skills, were not mentioned. However, upon further analysis, no drastic differences were found between the non-descript recommendation sets and those aimed at gamified systems for specific age groups.