Table 2.

Gamification elements included in the intervention.

Gamification element	Description
Dual-purpose game mechanics	All games designed to be both enjoyable and therapeutic, requiring the user to keep their gaze on a moving spider, with or without additional game mechanics. No included first-person movement, to both evoke common fear of invasion of private space by the spider and to avoid cybersickness.
Speed	Moving spider stimuli to evoke a greater fear response and prevent virtual reality-specific safety behavior of closing one’s eyes.
Goals	Clear goals for completion of each sublevel, conveyed verbally or visually.
Performance feedback	Scores displayed at all times and users could replay levels to achieve a higher score.
Badges and achievements	Visual summary of levels completed.
Dual-purpose narrative	Many sublevel games presented with a short narrative on task background and goal.
Points	Scoring key to game mechanic in gaze task and “boss” type sublevels, requiring a certain score to complete.
Levels	Familiar level design with levels and sublevels.
Increasing difficulty	Increasing spider realism with each level.
Onboarding/psychoeducation	First part of game features traditional cognitive behavioral therapy psychoeducation on phobia development and maintenance, and rationale for exposure.
Virtual helper	Voiceover virtual therapist, also presented as hologram avatar in the virtual therapist room, introduced at beginning of game and guiding the user throughout, giving instructions, encouraging progress and achievements, and summarizing key therapeutic points.