Nowadays, it is easy to find concepts for connecting mobile devices and looking at photos together. Despite the increasing interest in multi-device single display groupware (multi-device SDG), most of the existing research is limited to using a rectangular form array to enlarge the display. In this paper, we suggest a new way of assembling mobile devices to create unique forms, such as ring, bar, rectangle and radial shape displays, and investigate their inter-device interaction characteristics. We conducted generative workshops on a game domain to understand the characteristics of those interfaces. Directionality, interdevice space, and tangible interactions were extracted. By applying the derived characteristics, we have developed three different collaborative games using different types of interfaces. Through user studies of the developed games, we refined the characteristics and found additional design issues. The inter-device interaction characteristics and issues of multi-device SDG obtained from this study could be generally applied to collocated multi-mobile interactions.v