The rapid development of motion tracking, miniature displays, communication technologies, and the unique characteristics (immersion, realism, engagement) of immersive virtual reality (VR) technologies have changed the nature of gaming and, to a large extent, helped shape its future. The way players interact and experience VR games is very different from traditional platforms. For instance, VR players are moving from (1) 2D screen-based gaming to 360° gaming, (2) playing the character to being the character, and (3) limited sensory feedback to complete feedback (e.g., touch, taste, smell). Despite these changes, current research on VR games still relies primarily on user evaluation methods and approaches designed for traditional 2D screen-based games. As VR becomes more pervasive, more attention needs to be paid to designing, reconfiguring, or validating methods and approaches for evaluating gameplay and experiences in VR games.

There are several limitations of applying traditional questionnaires and methods for measuring VR gameplay: (1) traditional questionnaires have not been validated for VR games, (2) they are not designed for VR gaming, and the unique characteristics of VR gaming (e.g., immersion, sickness, fatigue) are often not included in their measurements, (3) it may interrupt the overall VR game experiences (e.g., sense of immersion) if used outside of VR. On the other hand, VR enriches performance data generated by the players and offers several physical movement data generated by the users, which might also provide insights into the overall gaming experience. Therefore, there is an urgent need to establish new and novel metrics for measuring VR games.

Several consumer-based headsets are now using (or compatible to include) physiological sensors, including eye-tracking, electroencephalography, and electromyography. As such, VR provides a golden opportunity for using real-time measures of human responses essential to the players' experience. Traditional physiological or biometrics such as eye-tracking and heart rate (i.e., attention and stress responses), electroencephalography and electromyography (e.g., cognitive load), emotions/expressions (e.g., users' feeling) could be considered and adapted for assessing VR gameplay experience, but they need to be validated. In addition, these physiological data have the potential to be used in real-time to improve the user and gameplay experience. Real-time use of such data remains largely underexplored.

This special issue focuses on exploring novel and state-of-the-art user evaluation methods for VR games. We are looking for model papers with high standard, rigorously tested user evaluation methods that other researchers can follow and build on. The special issue aims to bring together researchers from various backgrounds to report their novel methods, approaches, and designs to assess VR gameplay and experience.

Suggested topics include, but are by no means limited to:

• Metrics tailored for VR games
  • Performance
  • Experience
  • Physiological
• Methods and devices for measuring these metrics
  • Development of integrated physiological sensors in VR headsets
  • Development of algorithms for analysis of players' performance
  • Performance/Experience modeling
  • Studies that use physiological measurements in VR games
• Real-time adaptive gameplay and experience
• Dynamic in-game questionnaires
• Multimodal, multi-source measurements

• Abstract submission to guest editors and the EiC July 30, 2022
• Paper submission September 1, 2022
• First decisions November 30, 2022
• Early access SI publication (online) Early 2023
• Publication in print Late 2023

• Hai-Ning Liang Xi’an Jiaotong-Liverpool University, China Email: haining.liang [at] xjtlu.edu.cn
• Wenge Xu Birmingham City University, UK Email: Wenge.Xu [at] bcu.ac.uk
• Yiyu Cai Nanyang Technological University, Singapore Email: MYYCai [at] ntu.edu.sg
• Fotis Liarokapis CYENS – Centre of Excellence, Cyprus Email: f.liarokapis [at] cyens.org.cy

• User Experience of AI in Games - Guest editors: Henrik Warpefelt, Christoph Salge, Magy Seif El-Nasr, Jichen Zhu and Mirjam Palosaari Eladhari
• Evolutionary Computation for Games - Guest editors: Jacob Schrum (Southwestern University in Georgetown, USA), Anikó Ekárt (Aston University, UK), Cameron Browne (Maastricht University, NL) and Jialin Liu
• Evolutionary Computation for Game-playing - Guest editors: Jialin Liu (SusTech), Jacob Schrum (Southwestern University) and Marcus Gallagher (University of Queensland)
• Team AI in Games - Guest editors: Maxim Mozgovoy (University of Aizu), Mike Preuss (Leiden University), Tomoharu Nakashima (Osaka Prefecture University), and Rafael Bidarra (Delft University of Technology)

If you are interested in guest editing a special issue, you should send a proposal to the Editor-in-Chief.

1. Please prepare a Call for Papers which will ultimately be distributed. We would suggest that this is a maximum of one side of A4.
2. Please provide an additional page, that presents short biographies of the proposed guest editors and why they are qualified to guest edit a special of the Transactions of Games in the area being suggested.
3. The proposal will be sent to the journal’s Associate Editors for comment. You may be asked to revise the proposal and this iterative process will continue until a decision has been made.

• The proposed guest editors must include a current Associate Editor of ToG. This will ensure that the same standards are maintained for special issues, as for regular issues.
• A guest editor can submit a maximum of ONE paper with them as an author.
• A special issue cannot be related to a particular event (e.g. a conference) and submissions should be open to all
• The editorial that is eventually written to introduce the special issue must not mention specific conferences or events