Finding a missing child is an important problem concerning not only parents but also our society. It is essential and natural to use serendipitous clues from neighbors for finding a missing child. In this paper, we explore a new architecture of crowd collaboration to expedite this mission-critical process and propose a crowd-sourced cooperative mobile application, CoSMiC. It helps parents find their missing child quickly on the spot before he or she completely disappears. A key idea lies in constructing the location history of a child via crowd participation, thereby leading parents to their child easily and quickly. We implement a prototype application and conduct extensive user studies to assess the design of the application and investigate its potential for practical use.

Social exergames provide immersive experiences of social interaction via online multiplayer games, ranging from simple group exercises (e.g., virtual cycling/rowing) to more structured multiplayer games (e.g., cooperative boat racing). In exergame design, interpersonal synchrony plays an important role as it enhances social rapport and pro-social behavior. In this paper, we build ExerSync platform that supports various assistive mechanisms for facilitating interpersonal synchrony even with heterogeneous exercise modalities. We consider a rhythm of body movements in repetitive aerobic exercises and explore the design space of incorporating rhythm into exergames. We build a prototype system and comparatively evaluate the effectiveness of various assistive mechanisms. The experiment results show that rhythm significantly lowers the perceived workloads and provides better competence and engagement, but the accuracy of interpersonal synchrony is not dependent on the use of rhythm.

We demonstrate PosFree, a platform supporting posture-free motion-based mobile games. It allows the developers to support diverse postural gameplay contexts in the motion-based mobile games, without much knowledge on the specific characteristics of motion sensors with respect to posture changes. It detects orientation of mobile devices at runtime and automatically converts motion sensor data as if the devices are manipulated in the standard posture, as well as provides an intuitive user interface to help players understand their postural gameplay contexts. The platform prototype is currently implemented inside the Android Framework, and thereby off-the-shelf motion-based mobile games can utilize the feature of PosFree without modifying their original source codes.