## 3 Results
### Statistics of PRISMA-Based Screening  
The review followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flowchart for the screening and inclusion of articles in the final analysis (Figure 1). A total of 729 papers were retrieved from the four databases that we searched. Removing around 35.7% (260/729) of them for being duplicates, we had 469 left. Next, we commenced the first proper phase of screening, which was based on title and/or abstract. As shown in Table 3, there were 38 disagreements between the two researchers (KF and OI), in which 25 were only accepted by the former and 13 by the latter. There were 431 agreements between them, in which 16 and 415 were accepted and rejected, respectively, by both researchers. This resulted in an agreement rate of around 91.9% (431/469) and a \begin{table}
\begin{tabular}{l l} \hline \hline
**Characteristic** & **Description** \\ \hline Authors & Who wrote the paper \\ Year & What year the paper was published \\ Title & Title of the paper \\ Region of study & Which region the study featured in the paper took place in \\ Target population & Number and characteristics of participants in the study \\ Name of game & Name of the game featured in the paper \\ Game type & The type of game \\ Mnemonic type & What mnemonic type was used by the game \\ Target subject & What field the game and/or study was about \\ Design approach & Whether the design of the game was based on literature or user studies \\ User-evaluated & Whether users provided feedback regarding the game \\ Game mode & Whether the game involved interaction with other users or not \\ Age group & What age group the participants belonged to \\ Level of education & Whether the games were meant for people in kindergarten, elementary school, middle school, high \\ Game outcome & How effective the game was in improving users’ memory \\ System & Whether the game is for research purpose or available to the public to use \\ Aim/objective of paper & What was done in the paper’s study \\ Takeaway of findings & A brief summary of the game’s effect on its users \\  & Whether the game was meant to impart knowledge on a particular subject (educative), provide \\ Purpose & information such as news (informative), persuade people to behave a certain way (persuasive), or does \\  & not seem to focus on any of these (subjective) \\ Type of study & Whether the study’s data was qualitative, quantitative or mixed \\ Comparison & Whether an experimental group was compared against a control group, another experimental group, \\ Mnemonic generation & Whether the mnemonics were created by people or computers \\ Mnemonic source & Whether the mnemonics were created by players or games (or their creators) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Characteristics of included papers and their evaluated games. Cohen's Kappa of around 0.415. We screened out around 94.7% (444/469) of them by title and abstract, which meant we had 25 remaining. Finally, we performed the second phase of screening, which was based on full-paper review. As shown in Table 3, there were three disagreements between the two researchers ([PERSON] and OI), with all three associated papers accepted by the former only. There were 22 agreements between them, with 7 of the associated papers accepted by both and 15 rejected by both. This resulted in an agreement rate of 88% (22/25) and a Cohen's Kappa of around 0.737. We screened out 64% (16/25) of those based on a full-paper review, which would have resulted in us being left with 9 papers to report. However, the senior researcher ([PERSON]) realized that around 88.9% (8/9) of these papers did not feature mnemonics as they were only retrieved due to the generic \"memor\" term in our search strings aimed to ensure we retrieved as many papers as possible that focused on improvement of memory, but did not explicitly use the term \"mnemonics\" in the title, abstract or keywords. This meant we only had one paper left from the formal screening process.