Mobile augmented reality (mobile AR) enables
virtual content such as 3D models, animations and annotations to
be placed on top of a real world objects in any context. We
applied mobile AR to develop the Calory Battle AR exergame to
tackle worldwide childhood obesity. In this game the player finds
and defuses virtual calory bombs in a real world environment.
Specifically, we present the development of two game versions.
First prototype was created without a third party game engine
and it led to many challenges. To explore solutions to these
challenges, we created a new version of game with the Unity 3D
game engine. Using the Unity 3D, the game development process
was simplified. A mixed-method usability evaluation on children
and university students indicated that especially interaction with
AR content and user interface clarity were improved in the Unity
3D version. This study produced three important contributions:
1) a novel mobile AR exergame to motivate children to move; 2)
reimplementation of the game using the Unity 3D; and 3) results
of a usability evaluation comparing two game versions. We
expect that game engines such as the Unity 3D will become
essential for AR game development in the future.