Designing mobile game input unreachability: risks when placing items out of the functional area

Abstract: When planning controls for mobile games and gamified apps, designers consider how gamers access features and where to display them. With users potentially operating their devices single-handed, content producers have been using design approaches based on the screen area a thumb can reach when the hand supports the device, with different degrees of difficulty. Depending on the screen size, some parts are out of the thumb’s reach, requiring operation with the assistance of the other hand or changing grip when possible. Despite the common facilitated access to relevant game resources within the area, some items are intentionally placed in unreachable zones, trying to make gamers take longer until they can access them, thus increasing displayed content exposure. These hard-to-reach options are inputs to mute, forward, or close in-game advertising and in-app purchase offers. They disregard the potential uncommon thumb actions one may adopt to tap them. This paper studies single-handed thumb reachability in mobile games and the ads they display to identify how their screen design can provide different levels of performance and body safety to access specific content and then understand whether items out of the thumb’s reach can lead to potential risks for the gamer. While game design should contribute to interaction and comfort, promotional features seeking monetization have strategies to avoid or delay interaction, with risks of interfering with performance or thumb injuries.

Keywords: Mobile Gaming Risks, Mobile Device Interface Thumb Reachability, Mobile Screen Design Human Factors, Functional Area of the Thumb

DOI: 10.54941/ahfe1004994

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