Seamful design is a new approach to reveal and exploit inevitable technical limitations in Ubiquitous Computing technology rather than hiding them. In this paper we want to introduce its general ideas and apply them to the design of location-aware games for mobile phones. We introduce our own seamful trading-game called “Tycoon” to explore seams on this platform and show how to incorporate them into the design of mobile games. We want to evaluate how applications for the mobile phone platform which use cell-positioning can exploit seams for better interaction, gameplay and usability.