Finding “Astro”

An experimental mobile exergame to promote physical activity


March 2016 – April 2016


According to the Center for Disease Control (CDC) and World Health Organization (WHO), children between the age of 5-17 must get at least 60 minutes of daily physical activities. However, only 35% of this population adheres to these guidelines. Smartphones offer unique opportunities to help individual engage in physical activities by tracking bodily movements, deliver timely interventions, and enable seamless communication with other users.

We designed “Finding Astro”, an experimental exergame to promote small bouts of physical activity throughout the day. In this game, the player is tasked with finding a lost astronaut (named Astro) in the outer space. When the game starts, the astronaut appears on the screen for a split second and leaves the screen. The player has to follow astronaut’s direction by physically moving both hands (while holding the phone). As soon as the astronaut is captured on the screen, players gain some points and the astronaut disappears in another direction. If the player fails to capture astronaut within a  time-window, they lose the level and the game starts again.


To ensure that the players use both their hands for the exercise, we have added two buttons on the game screen. In order to play the game, players must press and hold these two buttons on the screen. Releasing either of the buttons ends the game. The green and red cross-air axes are provided to help players set their device orientation to absolute horizontal (i.e, device y and z acceleration is zero).

In the beginning, Astro is right at the center of the cross-air and drifts in a certain direction. Players have to follow this direction (as indicated on the screen). Motion detection in the game is done using accelerometer and rotation vector sensor. Each level in the game lasts for the finite amount of time. Time constraints are added to ensure high exertion on the player’s side in finding the lost astronaut. You can access the code here.

Technology Used: 

Android (accelerometer and rotation vector sensor), Firebase Cloud, Google Cloud Messaging


Game Design, Level Design, Interaction Design, Android Development

Skills Developed: 

Mobile application design and development, sensor-based programming


Binod Thapa-Chhetry (Ph.D. Student, Northeastern University)