Brick: a Synchronous Multiplayer Augmented Reality Game for Mobile Phones
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CHI 2019 Interactivity CHI 2019, May 4–9, 2019, Glasgow, Scotland, UK Brick: A Synchronous Multiplayer Augmented Reality Game for Mobile Phones Po Bhattacharyya Yein Jo Carnegie Mellon University Carnegie Mellon University Pittsburgh, PA Pittsburgh, PA [email protected] [email protected] Ketki Jadhav Radha Nath Carnegie Mellon University Carnegie Mellon University Pittsburgh, PA Pittsburgh, PA [email protected] [email protected] Jessica Hammer Carnegie Mellon University Pittsburgh, PA [email protected] ABSTRACT Multiplayer augmented reality (AR) games allow players to inhabit a shared physical environment populated with interactive digital objects. However, currently available games fall short because of either limited synchronicity or limited opportunities for player movement. Here, we present Brick, a synchronous multiplayer AR game at the room scale. Brick’s players collaborate to fill in a pattern of Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for third-party components of this work must be honored. For all other uses, contact the owner/author(s). CHI’19 Extended Abstracts, May 4–9, 2019, Glasgow, Scotland UK © 2019 Copyright held by the owner/author(s). ACM ISBN 978-1-4503-5971-9/19/05. https://doi.org/10.1145/3290607.3313257 INT009, Page 1 CHI 2019 Interactivity CHI 2019, May 4–9, 2019, Glasgow, Scotland, UK empty slots using digital "bricks" scattered about the room. This paper provides an overview of Brick from a design and technical perspective. It also discusses how Brick extends the current scope of AR games to include collaborative gameplay. KEYWORDS shared-world augmented reality, synchronous, collaborative INTRODUCTION Augmented reality (AR) games allow players to interact with digital objects placed in their physical surroundings. Over the years, game designers have typically focused on designing AR interactions for a single player [3, 6, 7, 13, 14]. But AR can also invite players to move beyond the interface and attend to the physical environment they share with other players [14]. Figure 1: A view of the pattern of empty Currently available AR games offer limited opportunities for a multiplayer experience. For example, slots and the bricks through the players’ many multiplayer games, such as Ingress [8] and Run an Empire [12], are asynchronous, i.e., they mobile devices. Each player is assigned require players to take turns during gameplay. Consequently, these games might be more accurately two colors, shown in the top-right of the described as a collection of colocated single-player experiences [2]. Other multiplayer games, such screen. ©Po Bhattacharyya as Pokémon Go [9], include synchronous interactions, but not in AR. As of December 2018, Pokémon Go’s multiplayer features, such as "gyms" and "trainer battles," are not supported in AR [10, 11]. Our survey of the current landscape yielded only two AR games—SwiftShot [1] and LightBoard [5]— that include synchronous multiplayer capabilities. These games allow multiple players to inhabit a shared world in AR. However, in both games, play is restricted to the tabletop and players are largely rooted in position, so the opportunities for attending to the physical environment are limited. DESIGN OF BRICK Here, we present Brick, a synchronous and collaborative AR game for two players at the room scale. In each round, the players work together to fill in a pattern of empty slots ("wall") using digital objects ("bricks") that are scattered all over the room (see Figure 1). The bricks come in four colors, andeach player can interact with two of those colors. Players collect and transport bricks using a tap-and-hold interaction in AR. Both players are actively collecting bricks throughout a session of gameplay; they do not take turns. To win, the players must fill in the entire wall before time runs out. Figure 2: A diagram showing the five main Brick is an example of a shared-world AR experience, in which players inhabit a shared, real- categories of interactions in a two-player time augmented environment and can engage in synchronous interactions with other players (see shared-world AR environment. ©Po Bhat- Figure 2) [2]. Brick offers five different types of interactions: single-player, intrapersonal, multiplayer, tacharyya interpersonal, environmental. See Table 1 for examples of each type of interaction. INT009, Page 2 CHI 2019 Interactivity CHI 2019, May 4–9, 2019, Glasgow, Scotland, UK TECHNICAL OVERVIEW Table 1: The five types of interactions in Brick was developed using Google’s ARCore technology [4]. Synchronous networking across multiple Brick, with examples. Android devices was essential for Brick to work; Brick’s players need to keep track of their own progress as well as that of their partner. However, establishing a networked environment turned out to Interaction Examples be a thorny problem, with little documentation and few precedents in the community. Using ARCore Single-player Transport individual bricks Cloud Anchors, we were able to create a stable body of code to support synchronous networking for Intrapersonal Emotion and cognition during play Brick and other games. Multiplayer Transport collaborative bricks We also created a custom network transform to sync each brick’s initial position as well as its rotation and movement once it is picked up by a player (see Figure 3). This was necessary since each Interpersonal Conversations and physical contact player is in a different coordinate space. The network transform converts position and rotation data Environmental Navigation and collision avoidance relative to the Google ARCore Cloud Anchor, so that the anchor can behave as a world pivot. See Figure 4 for a tehnical overview of our open-source code, made available on Github here: github.com/trie94/Love-Brick. FUTURE WORK We have playtested Brick with 14 participants. The overall response to the game has been positive, and we have also identified two ways in which Brick can be improved going forward. First, we believe that Brick’s intrapersonal, interpersonal, and environmental interactions can be technologically mediated. The current version contains a few examples of technologically mediated interactions. For example, players choose where in the room they should place the wall; we view this as a technologically mediated environmental interaction in which players have to navigate their physical space. We hope to add more such technologically mediated interactions to future versions of Brick. Second, we would like to add more variety to the game. For example, Brick could have levels in which players are required to complete patterns based on shape, size, and texture, not just color. Figure 3: A diagram showing how a net- Moreover, the brick transport interaction could also be varied. Possible variations on the current work transform is used to sync data from tap-and-hold interaction could be inspired by actions such as scoop, lasso, slam, and slap. the two players, each of whom is in a dif- ferent coordinate space. ©Yein Jo In conclusion, we view Brick as a valuable addition to the current landscape of AR games. Brick extends the current scope of AR games in two ways. First, by promoting active spatial movement, it grounds players in their physical reality. Second, by promoting collaboration during gameplay, it connects players with each other. We look forward to more research- and design-based explorations of Brick, as well as to other examples of synchronous multiplayer AR. INT009, Page 3 CHI 2019 Interactivity CHI 2019, May 4–9, 2019, Glasgow, Scotland, UK ACKNOWLEDGMENTS We thank Verizon for their generous support of our research. We thank Mengqi Wu and Yujin Ariza for contributing toward developing Brick in high fidelity. We also thank Yujin Ariza for contributing the background score for Brick. Finally, we are immensely grateful to our playtesters for their time, openness, and honest feedback, without which Brick would not have become a reality. REFERENCES [1] Apple. 2018. SwiftShot: Creating a Game for Augmented Reality. https://developer.apple.com/documentation/arkit/ swiftshot_creating_a_game_for_augmented_reality [2] Po Bhattacharyya, Radha Nath, Yein Jo, Ketki Jadhav, and Jessica Hammer. 2019. Brick: Toward A Model for Designing Synchronous Colocated Augmented Reality Games. (2019). https://doi.org/10.1145/3290605.3300553 (in press). [3] Yu-Ning Chang, Raymond Koon Chuan Koh, and Henry Been-Lirn Duh. 2011. Handheld AR games–A triarchic conceptual design framework. In Mixed and Augmented Reality-Arts, Media, and Humanities (ISMAR-AMH), 2011 IEEE International Symposium On. IEEE, 29–36. [4] Google. 2018. Introduction to ARCore–Augmented Reality Design Guidelines. https://designguidelines.withgoogle.com/ ar-design/ [5] Google. 2018. LightBoard: An AR Multiplayer game to demonstrate the Cloud Anchors API. https://opensource.google. com/projects/arcore-lightboard [6] Teemu H. Laine. 2018. Mobile Educational Augmented Reality Games: A Systematic Literature Review and Two Case Studies. Computers 7, 1 (2018), 19. [7] Zhihan Lv, Alaa Halawani, Shengzhong Feng, Shafiq Ur Réhman, and Haibo Li. 2015. Touch-less interactive augmented reality game on vision-based wearable device. Personal and Ubiquitous Computing 19, 3-4 (2015), 551–567. [8] Niantic. 2013. Ingress. https://www.ingress.com/ [9] Niantic. 2016. Pokémon Go. https://www.pokemongo.com/en-us/ Figure 4: A technical overview diagram [10] Janne Paavilainen, Hannu Korhonen, Kati Alha, Jaakko Stenros, Elina Koskinen, and Frans Mayra. 2017. The PokéMon GO Experience: A Location-Based Augmented Reality Mobile Game Goes Mainstream. In Proceedings of the 2017 CHI showing the main elements of Brick’s Conference on Human Factors in Computing Systems (CHI ’17). ACM, New York, NY, USA, 2493–2498. https://doi.org/10. Github repository. Network Manager, 1145/3025453.3025871 Cloud Anchor Manager, Game Manager. [11] Philipp A.