Using OpenSimulator, we constructed a 3D virtual playground that affords competition-themed social gaming, role-play gaming and design-themed architectural gaming among high-functioning autistic (HFA) children. A mixed-method, multi-case study was conducted to examine the association between the game task and setting features, learners' participation patterns, and their game-based social interaction performance. Eight 10-14-year-old HFA children participated in the study. Data were collected via screen recording and observation of participants' gaming actions and reactions. We conducted a behavioral analysis with the recorded social interaction performance of participants in the virtual gaming sessions. The study found that virtual reality-based gameplay promoted the social interaction performance of HFA children. The study findings also suggested that gameplay should be adapted based on the competencies and in-situ reactions of learners.