Table 4.

Corresponding criteria of the GameFlow element control and their implementation and fulfillment in the story game.

Control criteria	Implementation in the story game	Fulfillment status
A sense of control over the game avatar and its movements and interactions	During the main intervention task, it was not possible to exercise control over the game avatar. However, following the main intervention task, players were able to customize their avatar or buy new avatars in the avatar customization system, all of which or whom appeared later on the platforms in the virtual hub world. However, as the avatars automatically jumped to the next stage when finishing a session, their movement and interaction control was limited.	Partly
A sense of control over the game interface and device	As children aged 5 years are relatively familiar with tablets in recent times, we believed that the tablet was a suitable device for the intervention program. Moreover, individual player profiles were set in advance on each tablet, and the main menu contained no other option than starting or stopping the game, making the game interface intuitive and self-explanatory.	Yes
A sense of control over the game mechanics (saving and stopping)	Players were able to start and stop the game anytime. However, when interrupting the game during story listening, the progress of the ongoing session was not registered or saved, and players should restart the whole session.	Partly
Errors that will harm the game (eg, bugs) should not occur, and if they occur, support must be available	The game was piloted many times on members of the research group and on children with a similar age as the target group. Although the game appeared bug free at the end of the pilot studies, some players in the actual intervention study (not included in the final data analysis) experienced bugs causing a total crash of the game and loss of in-game data. In those cases, a member of the research group provided support as soon as possible by reinstalling the game at the homes of the players.	Partly
A sense of control over the game world (possibility to shape the game world)	Following the main intervention task and the time spent in the avatar customization system to change the game avatar, the newly dressed or new game avatar appeared in the virtual hub world on one of the stages. In that sense, players exercised control over altering their game world. However, the background animations and models in the hub world were preprogrammed and could not be altered.	Partly
A sense of control over the game actions and strategies	As the order and goal of the game, along with the framed intervention task, was fixed for all players, it was not possible to make use of different strategies and actions to reach the end of the game.	No