Purpose: This paper aims to describe the design and user testing of GeoForge, a multiple-player digital learning experience for middle school that leverages virtual reality (VR) and individualized websites for learning concepts in planetary science. This paper investigates how specific instructional design choices and features of the technology fostered collaborative behaviors. Design/methodology/approach: GeoForge was implemented in 3 middle school classrooms with a total of 220 students. Learners used GeoForge in class in groups of 3-4 to learn about planetary science. A mixed-methods approach examined collaboration using classroom observations, teacher interviews, student surveys and student artifacts. Using Jeong and Hmelo-Silver's (2016) seven affordances of technology for collaborative learning, this paper identifies ways in which features of GeoForge supported collaborative behaviors. Findings: Instructional design which combined VR and the digital science journal (DSJ) helped foster collaboration. Some collaborative behaviors were especially notable in classrooms that did not regularly practice these skills. Segmenting tasks in the DSJ, clarifying instructions to articulate ideas, showing other group members' responses onscreen and enabling multiuser VR environments contributed to collaborative behaviors and a satisfying learning experience as observed and documented through multiple methods. Originality/value: GeoForge successfully integrated VR and personalized websites in a classroom planetary science lesson, an approach which balanced instructional design and logistical challenges while creating opportunities for collaboration.