Contents I. Introduction
In many crowded metropolitan cities, people often travel by public transports like metro and local buses everyday. A finding shows that about 3,000 commuters in the west of England spend about 139 hours a year on average traveling to and from their work place [1]. Therefore, mobile computing in crowded public transports can open up a new opportunity to harness a collection of smart devices (e.g., smartphones and tablets [2], [3]) in their vicinity as a unified computing substrate. Figure 1 shows a snapshot of the Beijing Underground where most of crowded passengers are looking at their smart devices. A promising aspect we focus in this paper and our research path in its own right, is to enable highly-interactive and opportunistic multi-player gaming [4]–[6] among the crowd. Examples of these games are first-person-shooting (FPS) and racing. In it, users play and exchange their game play information dynamically among the crowd, however they come with many challenges.
