Application of the Artificial Society Approach to Multiplayer Online Games: A Case Study on Effects of a Robot Rental Mechanism Ruck Thawonmas and Takeshi Yagome Intelligent Computer Entertainment Laboratory Department of Human and Computer Intelligence, Ritsumeikan University Kusatsu, Shiga 525-8577, Japan ruck@ci.ritsumei.ac.jp Abstract This paper discusses a case study where the artifi- cial society approach is used to examine effects of a robot rental mechanism in a multiplayer online game, under development at the authors’ laboratory. Simula- tion results show the effectiveness of the proposed rental mechanism, namely, better game balance and inflation control. These results also indicate that the artificial society approach has high potential for use in multi- player online game applications in order to systemati- cally predict effects of each service or component. 1. Introduction Development of multiplayer online games involves high costs. A major reason for this is that effects of each service or component are hardly known before launching of beta versions. To remove unwanted ef- fects or add more wanted effects, ad hoc development is forced to continue after releasing of the games. This paper aims to present a solution to the above issue. Our solution is to use the artificial society ap- proach [1, 2] for analyzing each service or component in advance. In the artificial society approach, computer simulation is used to explore and understand social and economic issues. The approach has been widely used since 1990s among social scientists. In this paper, based on the artificial society ap- proach, we study effects of introducing a robot rental mechanism into a multiplayer online game called ”The ICE”. 2. Game concepts of The ICE Here we describe the game concepts of The ICE. This game is under development at the authors’ labo- ratory using a customized middleware of Community Engine Inc [3]. Besides educational purpose, it will be used as a platform for examining various data mining techniques in [4-6], recently proposed by the authors’ group and tested on a multiplayer online game simula- tor called Zereal [7]. In The ICE, each player is initially given a pro- grammable robot. A major role of the player is that of programming the robot and participating with it in a snow battle at a battle field against the team of an- other player and his robot. A reward is distributed to the winner player of the battle. The fun of this game is the in-game programming. Though they might have difficulty in programming their robots in the beginning, through trial-and-error processes and advices from virtual friends or Game Masters, players should gradually overcome such hur- dles step by step. They should also become more and more attached to their own robots. However, there might be some players who have a relatively low pro- gramming ability. Rather than preventing this type of players from playing the game, we propose below a robot rental mechanism for balancing the player sta- tus, in terms of the amount of virtual money in hand versus the robot performance. This should result in higher player satisfaction. 3. Robot rental mechanism and its eco- nomical perspective The proposed robot rental mechanism is outlined as follows: