stock prices and weather. The main idea is that these
computing devices and their interfaces are either “hidden” in
the background or are not made very explicit or intrusive. As
such, the emphasis is given to the user’s normal and natural
environment, and computing becomes less distracting and a
part of the ambience of that environment.
Similarly, Pervasive Gaming refers to a game where the
users play in a real environment (city streets, backyards,
forests, gyms, clubs, etc.) doing real physical activity, yet the
game is run with the assistance of pervasive sensors and
computing nodes which connect the players. Most of these
games use some sort of positioning technology and/or sensors
to track the player's location. With the advent of small and
cheap sensors such as Radio Frequency Identification (RFID)
and Bluetooth, Pervasive Gaming applications such as Turf
Wars [7] or Parallel Kingdom [8] have become affordable and
practical. The technology has the potential to play a major role
in obesity rehabilitation, due to offering an engaging physical
activity in the form of gaming attractive especially to children
and youth, as well as providing the ability for accurate
measurement of various player parameters such as energy
intake and consumption.
II. RELATED WORK
A number of recent efforts have attempted to address the
issues of obesity through digital games. Play, Mate! [9] is an
interface and design method for traditional computer games
which motivates users to perform physical activities that lead to
changing the game difficulty level depending on user's
performance in the game. Exertion Interfaces [10] aims at
increasing the physical activity of computer users stating that
persuasive physical activity intervention will contribute to
overall wellbeing. Fizzees [11] is an early prototype of an idea
of a single-user digital game that runs on a wrist mounted
device and comes with an accelerometer and a heart rate
monitor chest strap. It monitors the user’s physical activities
which trigger the game. The game itself is about taking care of
a “digital pet”. The only way to interact with the game is the
physical actions of the user. The device does not offer any
traditional input interfaces and users themselves must live in
healthy ways to succeed in the game. NEAT-o-Games [12]
collects user activity data from a wearable accelerometer which
controls the animation of an avatar that represents the user in a
virtual race game running on his/her cell phone and playing
with other players over the cellular network. Similar to the
approach presented in [12], Goudarzi et al. [13] develop
PEDdo, a device which encourages physical activity of its users
in and reinforces positive exercise habits.
MacLellan et al. [14] perform measurements of physical
activity and the location of users to promote the utilization of
walking as a form of transportation as a primary mechanism to
encourage people to become more active. Their system tries to
assist players in understanding their current physical activity
levels and identifying further changes required in order to meet
their goals. To measure the physical activity, they use
activePAL from PAL Technologies Ltd. to derive the total
energy expenditure, although the development of an improved
measurement system was not addressed. Toscos et al. [15]
propose “Chick Clique”, a mobile application which motivates