Press A or Wave: User Expectations for NPC Interactions and Nonverbal Behaviour in Virtual Reality

Non-playable characters (NPCs) are important in games, as they can provide guidance to the player, create social engagement, and advance the game's narrative. Although much research exists regarding NPC interactions for traditional gaming environments, e.g. desktop or console, fewer works have considered this from a virtual reality (VR) perspective. Our work first uncovers the salient and unique dimensions of VR NPC interactions through observations of 47 existing games. We find that VR NPC interactions have an extended set of interaction mechanisms due to two key factors - interaction triggers and player constraints within the game, driven by the unique qualities of physical motion and immersion afforded by the medium. We augment these findings through a user study performed on 18 participants in a VR environment. Participant interactions with a responsive NPC allow us to delve deeper into understanding player perception and expectations of NPC behaviour and interactions. Our findings outline player expectations for NPC realism, player agency during NPC interaction, and NPC expected behaviour and feedback. We tie our findings into discussions on player agency within VR, highlighting design suggestions to develop NPCs to better fit within social behaviour expectations.