## 2 Materials and Methods
### Data Charting Process and Items  
To evaluate games effectively, [PERSON] et al. [40] recommended that the evaluation be carried out on the basis of four criteria, which they referred to as groundings. They include technical, empirical, external and theoretical groundings. Technical grounding entails considering the technical and operational feasibility constraints and adapting them accordingly as practically feasible. External grounding requires that the evaluation be conducted in real-world settings to increase its relevance. Empirical grounding entails using multiple evaluation methods (e.g., quantitative and qualitative) to increase generalizability and avoid basing conclusions on a single method. Theoretical grounding requires that the evaluation be informed by relevant established theories. Given the authors' primary objective of writing the paper (heuristic evaluation) and technical constraints, we chose one author-determined generic set of criteria, two established theoretical evaluation frameworks, and two experts to evaluate the apps retrieved from the app stores. The two experts included one user experience (UX) Master's student (KF) and one third-year UX undergraduate student (OI), both of whom were guided and supervised by a human-computer interaction (HCI) professor and researcher (KO). The generic assessment criteria are shown in Table 2. The theoretical frameworks include serious-game characteristics (Table 3) and experiential-learning characteristics (Table 4). The three sets of criteria address the first, second, and third research questions, respectively. General app characteristics include app name, cost, publication year, subject the game is about, and purpose. The serious game characteristics, which foster motivation, engagement, and learning, are based on [PERSON] et al. 's framework [41], which, for easy recall, we christened \"IN-3 PACIFIC\" (Immersion, Narrative, 3 Presentes, Agency or Control, Identity, Feedback, Interactivity, Challenge). While this list of interrelated game elements is not definitive or exhaustive, [PERSON] et al. stated it reflects \"how serious game designers, and game designers in general, have structured game development... and how researchers have examined aspects of game play that contribute to engagement and learning\" (p. 337) [41]. Moreover, the experiential learning characteristics are based on [PERSON]'s [42] revised [PERSON]'s [43] framework of experiential learning. Experiential learning is a \"learning by doing\" method of instruction, in which learners are involved, engaged, and actively participate in the learning process. Informed by [PERSON]'s [44] constructivist theory, it is a \"hands-on\" task-oriented learning process based on direct experience. [PERSON]'s [43] experiential learning cycle, comprising four stages, constitutes one of the most influential and cited theories of experiential learning. [PERSON] [42] identified five broad themes that characterize experiential learning, which we christened \"C-SHARP,\" for easy recall (see Table 4). They include Critical Reflection, Situated in Context, Hands-on Activity and Participation, Risk/Novel Experience, and Pragmatic/Purposeful. We chose these two frameworks (IN-3 PACIFIC and C-SHARP) for the evaluation of the mnemonics apps because they address the critical aspects of games and experiential learning, such as interactivity, feedback, challenge [41], user participation, and reflection [42]. KF and OI each noted in their own Google Sheet which apps fulfill which IN-3 PACIFIC and C-SHARP characteristics, before putting their decisions together in another Google Sheet. To maximize inter-rater reliability, KO thoroughly explained each characteristic to the two beforehand and kept the descriptions in a Google Sheet to ensure there were no misinterpretations.