Game interface enhancement under smartphone platform focused on touchscreen interaction Yoon-Hyun Kim, Ji-Hyun Lee ⇑ Graduate School of Culture Technology, KAIST, Daejeon 305-701, Republic of Korea article info Article history: Received 8 May 2014 Received in revised form 18 November 2014 Accepted 19 November 2014 Available online 26 November 2014 Keywords: Fighting action game Game interface design Touchscreen interaction Smartphone platform Two handed thumbs abstract Virtual game controllers are essential for particular game genres where the game contents are trans- planted from various platforms into a smart-phone platform. Virtual images are projected as a game interface at the smartphone’s output screen. Therefore, a certain amount of space needs to be abandoned for the controller’s interface projection. In addition, the functions of the game contents are fundamentally limited, thus eliciting the necessity of a limited number of buttons. In this study, diverse types of inter- action that occur between the user and touch-screen were researched, and adequate interactions for smart-phone game contents were extracted and analyzed. In addition, the focus is placed on minimizing the number of controller buttons while including diverse functions at the contents level. Notably, the study pointed out that previous virtual game controllers are a mere metaphor of traditional methods, thus limited to Tap interaction. By analyzing fighting action game contents, the Tap interaction is enhanced by adding Flick and Multi-touch interaction to diversify and enhance previous interaction values. Finally, a prototype was developed by ameliorating past interfaces and referring to the intrinsic features of the aforementioned types of interaction, followed by user evaluation. A previous question- naire method was adjusted to the particular research purpose, and quantitative evaluation was con- ducted while documenting and analyzing the user-log data of repetitive experiments. The results show that Flick and Multi-touch interaction techniques are beneficial under a smartphone touchscreen environment beyond the traditional Tap-only. Furthermore, functions are maintained with a minimum number of buttons while the situation compatibility of user interaction is verified. This study also shows that adding diverse types of interaction to the simple Tap-only affords a distinctive user experience of long-term interest and fun to the players that were previously restricted to the accustomed Tap-only. The results authenticate the applicability of the intrinsic fun mechanism to the smartphone based touchscreen game interaction. The study has implications in enhancing the traditional Tap-only based virtual game controller, which is a mere metaphor of controllers loaded onto other platforms, through proposing a tailored interface design and evaluation method under a smartphone platform. Furthermore, this study contributes objective reference source for the engineers to design future game contents, interface and heuristics evaluation in the platform. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction A smartphone is a mobile phone that is technically and functionally developed from former feature phones (Kim, 2010; Nham, 2010). According to a review by Mac Rumors (2011), smart- phone games occupy 34% of portable game industry and 8% of all of the platforms, excluding PC online games and PC games. The research shows that smartphone games are holding the place as a new platform in the game industry domain. Based on research conducted by Industry Games on the purchasing trend of game players (2010), players have recently been buying more smart- phone game titles than portable games such as PSP and NDS (Kweon, Kim, & Choi, 2011). Unlike antecedent mobile phones, smartphones possess a high-level of specifications in regard to hardware and functions. That implies that the aforementioned growth of the mobile game market is heavily related to the vitali- zation of smartphone propagation. As a result of this tendency, var- ious genres and contents of games formerly accessed through PC and video game consoles are currently shown on the new platform (Choi, 2011). In other words, the game titles once attractive in other platforms are transplanted to the smartphone platform. In http://dx.doi.org/10.1016/j.cie.2014.11.017 0360-8352/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: Graduate School of Culture Technology, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea. Tel.: +82 42 350 2919, mobile: +82 10 5020 2919; fax: +82 42 350 2910. E-mail address: jihyunlee@kaist.ac.kr (J.-H. Lee). Computers & Industrial Engineering 80 (2015) 45–61 Contents lists available at ScienceDirect Computers & Industrial Engineering journal homepage: www.elsevier.com/locate/caie