Impact of a Non-Playable Character on Player Experience and Performance in VR Games
Resumo
Serious games in virtual reality are valuable tools for therapy but can feel intrusive when users lack experience with the technology or must contend with excessive hardware—particularly head-mounted displays (HMDs). Introducing social elements, such as non-player characters (NPCs), into therapeutic games may help make the experience more comfortable and less invasive for the user. In this work, we implement and evaluate the effects of an NPC within a virtual reality serious game. The developed game encourages arm movements and features a fox avatar, which offers contextual tips and accompanies the player throughout the therapy session. Data analysis revealed that, although players’ performance was modestly impaired by distraction from the NPC, nearly all participants reported that the gameplay felt more enjoyable with the character’s presence. Additionally, specialist testing highlighted positive aspects of the experience and emphasized the NPC’s potential to enhance player motivation in therapeutic contexts. These findings can inform future research aimed at designing interactions that foster a more natural rapport between player and NPC—free from time pressure—and thus enable a more immersive and comfortable therapeutic experience.
Palavras-chave:
NPC, Virtual Reality, serious games, rehabilitation, motivation
Referências
Schiavinato, A. Machado, B. Pires, M. and Baldan, C. Influencia da realidade virtual no equilibrio de paciente portador de disfuncao cerebelar. Revista Neurociencias, 19:119–127, 2001.
Blackman, S. Serious games...and less! SIGGRAPH Comput. Graph. 39(1):12–16, 2005. DOI: 10.1145/1057792.1057802
Ribeiro, E. Brandao, A. Guimaraes, M. Rocha, L. Brega, J. R. and Dias, D. R. Um framework de rastreamento corporal para reabilitacao neuromotora com suporte a aplicativos multimidia. In Proceedings of the XXVI Symposium on Virtual and Augmented Reality, 292–300, 2024.
Valente, F. R. Guimaraes, M. D. P. Cirilo, E. J. R. Brandao, A. F. and Dias, D. R. C. A framework for neuromotor and neurofunctional rehabilitation using multi-agent systems. In Proceedings of the 24th Symposium on Virtual and Augmented Reality (SVR ’22), 142–150, 2024. DOI: 10.1145/3604479.3604524
Andreikanich, A. Santos, B. S. Amorim, P. Zagalo, H. Marques, B. Margalho, P. Lains, J. Faim, F. Coelho, M. Cardoso, T. and Dias, P. An exploratory study on the use of virtual reality in balance rehabilitation. In 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 3416–3419, 2019.
Novak, D. Nagle, A. and Riener, R. Can two-player games increase motivation in rehabilitation robotics? In 9th ACM/IEEE International Conference on Human-Robot Interaction (HRI), 447–454, 2014.
Ameri, K. Battegazzorre, E. Galletti, C. Bottino, A. Podda, J. Tacchino, A. Brichetto, G. De Michieli, L. and Barresi, G. Effects of social conditions in a virtual exergame for cognitive rehabilitation in multiple sclerosis. In IEEE 13th International Conference on Consumer Electronics - Berlin (ICCE-Berlin), 117–122, 2023.
Gabele, M. Weicker, J. Wagner, S. Thoms, A. Husslein, S. and Hansen, C. Effects and ways of tailored gamification in software-based training in cognitive rehabilitation. In Proceedings of the 29th ACM Conference on User Modeling, Adaptation and Personalization (UMAP ’21), 158–168, 2021. DOI: 10.1145/3450613.3456828
Freeling, B. Lecuyer, F. and Capobianco, A. Petting a cat helps you incarnate the avatar Influence of the emotions over embodiment in VR. In IEEE International Symposium on Mixed and Augmented Reality (ISMAR), 141–149, 2022.
Guo, Z. Xu, W. Zhang, J. Wang, H. Lo, C.-H. and Liang, H.-N. Who’s watching me? Exploring the impact of audience familiarity on player performance, experience, and exertion in virtual reality exergames. In IEEE International Symposium on Mixed and Augmented Reality (ISMAR), 622–631, 2023.
Yu, K. Wen, S. Xu, W. Caon, M. Baghaei, N. and Liang, H.-N. Cheer for me effect of non-player character audience feedback on older adult users of virtual reality exergames. Virtual Reality, 27(3):1887–1903, 2023.
Korkiakoski, M. Sheikhi, S. Tapio, K. Nyman, J. Saariniemi, J. and Kostakos, P. An empirical evaluation of AI-powered non-player characters’ perceived realism and performance in virtual reality environments. SSRN Preprint, 2024. [link]
Kojic, T. Vergari, M. Podratz, M. and Moller, S. The influence of extended reality and virtual characters’ embodiment levels on user experience in well-being activities. In IEEE Conference on Virtual Reality and 3D User Interfaces Workshops (VRW), 855–856, 2024.
Johnsen, K. Ahn, S. J. Moore, J. Brown, S. Robertson, T. P. Marable, A. and Basu, A. Mixed reality virtual pets to reduce childhood obesity. IEEE Transactions on Visualization and Computer Graphics, 20(4):523–530, 2014.
Nam, H. Lee, K. Park, J.-I. and Kim, K. AR Fitness Dog Effects of a user-mimicking interactive virtual pet on user experience and social presence in physical exercise. IEEE Transactions on Visualization and Computer Graphics, 31(5):2817–2827, 2025.
Pxltiger. Toon Fox. Unity Asset Store, 2020. Accessed November 3, 2024. [link]
Ryan, R. Control and information in the intrapersonal sphere An extension of cognitive evaluation theory. Journal of Personality and Social Psychology, 43:450–461, 1982.
Blackman, S. Serious games...and less! SIGGRAPH Comput. Graph. 39(1):12–16, 2005. DOI: 10.1145/1057792.1057802
Ribeiro, E. Brandao, A. Guimaraes, M. Rocha, L. Brega, J. R. and Dias, D. R. Um framework de rastreamento corporal para reabilitacao neuromotora com suporte a aplicativos multimidia. In Proceedings of the XXVI Symposium on Virtual and Augmented Reality, 292–300, 2024.
Valente, F. R. Guimaraes, M. D. P. Cirilo, E. J. R. Brandao, A. F. and Dias, D. R. C. A framework for neuromotor and neurofunctional rehabilitation using multi-agent systems. In Proceedings of the 24th Symposium on Virtual and Augmented Reality (SVR ’22), 142–150, 2024. DOI: 10.1145/3604479.3604524
Andreikanich, A. Santos, B. S. Amorim, P. Zagalo, H. Marques, B. Margalho, P. Lains, J. Faim, F. Coelho, M. Cardoso, T. and Dias, P. An exploratory study on the use of virtual reality in balance rehabilitation. In 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 3416–3419, 2019.
Novak, D. Nagle, A. and Riener, R. Can two-player games increase motivation in rehabilitation robotics? In 9th ACM/IEEE International Conference on Human-Robot Interaction (HRI), 447–454, 2014.
Ameri, K. Battegazzorre, E. Galletti, C. Bottino, A. Podda, J. Tacchino, A. Brichetto, G. De Michieli, L. and Barresi, G. Effects of social conditions in a virtual exergame for cognitive rehabilitation in multiple sclerosis. In IEEE 13th International Conference on Consumer Electronics - Berlin (ICCE-Berlin), 117–122, 2023.
Gabele, M. Weicker, J. Wagner, S. Thoms, A. Husslein, S. and Hansen, C. Effects and ways of tailored gamification in software-based training in cognitive rehabilitation. In Proceedings of the 29th ACM Conference on User Modeling, Adaptation and Personalization (UMAP ’21), 158–168, 2021. DOI: 10.1145/3450613.3456828
Freeling, B. Lecuyer, F. and Capobianco, A. Petting a cat helps you incarnate the avatar Influence of the emotions over embodiment in VR. In IEEE International Symposium on Mixed and Augmented Reality (ISMAR), 141–149, 2022.
Guo, Z. Xu, W. Zhang, J. Wang, H. Lo, C.-H. and Liang, H.-N. Who’s watching me? Exploring the impact of audience familiarity on player performance, experience, and exertion in virtual reality exergames. In IEEE International Symposium on Mixed and Augmented Reality (ISMAR), 622–631, 2023.
Yu, K. Wen, S. Xu, W. Caon, M. Baghaei, N. and Liang, H.-N. Cheer for me effect of non-player character audience feedback on older adult users of virtual reality exergames. Virtual Reality, 27(3):1887–1903, 2023.
Korkiakoski, M. Sheikhi, S. Tapio, K. Nyman, J. Saariniemi, J. and Kostakos, P. An empirical evaluation of AI-powered non-player characters’ perceived realism and performance in virtual reality environments. SSRN Preprint, 2024. [link]
Kojic, T. Vergari, M. Podratz, M. and Moller, S. The influence of extended reality and virtual characters’ embodiment levels on user experience in well-being activities. In IEEE Conference on Virtual Reality and 3D User Interfaces Workshops (VRW), 855–856, 2024.
Johnsen, K. Ahn, S. J. Moore, J. Brown, S. Robertson, T. P. Marable, A. and Basu, A. Mixed reality virtual pets to reduce childhood obesity. IEEE Transactions on Visualization and Computer Graphics, 20(4):523–530, 2014.
Nam, H. Lee, K. Park, J.-I. and Kim, K. AR Fitness Dog Effects of a user-mimicking interactive virtual pet on user experience and social presence in physical exercise. IEEE Transactions on Visualization and Computer Graphics, 31(5):2817–2827, 2025.
Pxltiger. Toon Fox. Unity Asset Store, 2020. Accessed November 3, 2024. [link]
Ryan, R. Control and information in the intrapersonal sphere An extension of cognitive evaluation theory. Journal of Personality and Social Psychology, 43:450–461, 1982.
Publicado
30/09/2025
Como Citar
LÊU, Matheus O.; NUNES, Fatima L. S.; PERES, Fabiana; TEIXEIRA, João Marcelo.
Impact of a Non-Playable Character on Player Experience and Performance in VR Games. In: SIMPÓSIO DE REALIDADE VIRTUAL E AUMENTADA (SVR), 27. , 2025, Salvador/BA.
Anais [...].
Porto Alegre: Sociedade Brasileira de Computação,
2025
.
p. 413-422.
