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Supporting Immersive Location-Based Games on
Resource-Constrained Platforms
Katsiaryna Naliuka
Trinity College Dublin
katsiaryna.naliuka@ndrc.ie
Tara Carrigy
Trinity College Dublin
tara.carrigy@ndrc.ie
Natasa Paterson
Trinity College Dublin
natasa.paterson@ndrc.ie
Roisin Cotton
Trinity College Dublin
cottonr@tcd.ie
Søren K. Jensen
Trinity College Dublin
Soren.Jensen@ndrc.ie
Mads Haahr
Trinity College Dublin
Mads.Haahr@cs.tcd.ie
ABSTRACT
This paper is concerned with challenges and solutions related
to the use of smartphones as a location-based mobile gam-
ing (LBMG) platform. We present here a summary of our
experiences from building a feature-rich story-driven LBMG
for the Android platform. The game uses location, handset
orientation and marker-less augmented reality to support its
core mechanics, which in turn support a strong story line.
Categories and Subject Descriptors
K.8.0 [Computing Milieux]: Personal Computing—games
1. INTRODUCTION
Smartphones are emerging as a personal computational
platform of significant popularity. The latest generation of
handsets (iPhone 4, Android 2 devices, etc.) are equipped
with a sophisticated combination of excellent media capabili-
ties (screen, GPU, audio) and considerable processing power
and memory. Features such as GPS, compass and cam-
era make smartphones attractive for location-based mobile
games (LBMGs), a genre which in digital form has existed
for around a decade, but which has yet to reach widespread
adoption. Despite the recent advances, challenges remain in
relation to the use of smartphones as game platforms:
Battery power is of course crucial to the operation of any
location-based mobile game, but smartphones are de-
signed to be feature-rich, rather than power-efficient [2].
User interfaces constitute scarce resources in several re-
gards. Most notably, screen real estate is extremely
valuable on a handheld device and must be used care-
fully.
Storage capacity in the form of RAM is a crucial resource
on the current smartphones in relation to games.
Processing power in the form of CPU cycles is also a cru-
cial resource, even despite the relatively powerful pro-
cessors found in the current generation of smartphones.
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Location-dependent information in the classification by
Forman et al. means that access to information changes
with the location of the device [2]. A particular chal-
lenge is that knowledge about the location can vary
significantly.
In the next sections we briefly describe the design prin-
ciples behind our game (Sec. 2) and the technical solutions
that we adopted to deal with the above mentioned challenges
(Sec. 3). Concluding remarks (Sec. 4) end the paper.
2. GAME AND STORY DESIGN
Viking Ghost Hunt (VGH) is a location-based adventure
game. In this game the player assumes the role of a para-
normal investigator and moves around the city hunting for
ghosts and solving the mysteries of haunted Viking Dublin
(800–1169 AD). The game can be considered a hybrid of
a mystery game and Gothic ghost story. Importantly, it
takes place in locations that are of direct historical signif-
icance to the material and which are chosen to help the
player achieve a high degree of immersion. The game is
story-driven in the sense that, in order to progress the game,
the player must unlock a sequence of distributed, location-
specific, story fragments, which together make up a mean-
ingful story arc. Hence, the VGH story, which is mapped
onto actions and space, is revealed through the players’ ac-
tivities as they move through the locations and, in order
to preserve the aesthetics of the role-play, these activities
are presented in the context of paranormal investigation. In
this form of storytelling, the player is not an external ob-
server, but becomes an agent, who advances in the game
and progresses the story by interacting with narrative ele-
ments, such as location, character and plot line. The game
progress is enabled by the following core mechanics:
Navigation Mechanics The player must identify and move
to a particular haunting as marked on a map.
Search Mechanics Once within the haunted area, the player
must use the paranormal radar to find manifestations
of ghosts in the form of audio and visuals (see Fig. 1).
Scan/Capture Mechanics Once a ghost has manifested
visually, the player must take photos of it as evidence.
The audio manifestations must be recorded and de-
coded. Once the evidence is collected new ghost man-
ifestations appear. In this way the player unlocks new
parts of the story.
102
Paranormal activity also manifests itself through the back-
ground soundscape that creates the atmosphere of a haunted
place. Its intensity varies through the mission. For detailed
discussion of sound and game design please see [3, 1].
3. TECHNICAL IMPLEMENTATION
The design features that have the most impact on the
implementation can be summarized as follows. The game
is location-based and includes elements of augmented real-
ity. It is also media intensive to support audible and visible
ghost manifestations and background sounds, which makes
resource management a primary concern. The last feature
for consideration is the fact that the game is story-driven,
and consequently game missions have a relatively complex
structure. In the following, we describe how implementation
of these features is affected by the previously enumerated
challenges of resource-constrained platforms.
Dealing with GPS Inaccuracy. GPS accuracy in urban
environments tends to be mediocre at its best. We employed
several strategies to deal with this issue. The most obvious
was selecting the areas, in which GPS reception generally
tended to be better (e.g., selecting open places rather than
those shadowed by trees or buildings). However, since sites
of varying character are required to create immersion in the
game, this solution turned out to be insufficient and rather
unreliable. Another idea that we employed was using regions
of complex shapes (rather than simple circles) to trigger the
game events. Using polygonal regions allows increasing size
of the region, which makes it easier for players to progress
through the game, yet at the same time it leaves more free-
dom for positioning regions without overlapping.
Augmented Reality (AR). The main challenge in AR
lies in the anchoring of the image on top of the camera
stream. This requires tracking the player’s view point ei-
ther by analyzing the video stream from the camera or using
the orientation sensors. Because of the battery and process-
ing power limitations the first approach, to our knowledge,
has not been fully implemented on mobile devices till date,
except with the use of fiduciaries, which were not an op-
tion in our urban environment. We relied on the second
approach, mitigating the negative impact of sensor inaccu-
racy by filtering. In addition we created a form of AR audio
by using spatialization, reverberation and binaural recording
techniques [3] to realistically match the game’s sound effects
to those naturally occurring in the environment as way of
deliberately creating ambiguity between the game and the
environment.
Resource Management. There are two issues in An-
droid that complicate resource management. First, even
though devices have RAM modules of impressive capacity
the limit on memory available for each application is rel-
atively low (16 Mb in our targeted version of Android).
Therefore early preloading of the resources into memory is
undesirable. At the same time, the processing power of the
handsets remains comparatively low. In Android this prob-
lem is exacerbated by the fact that applications must be
developed in Java, which involves the use of a virtual ma-
chine. The implications are that loading resources takes
relatively long. The outcome is that loading resources in
parallel with any computation-heavy routine can render the
device unresponsive. The solution we adopted was to load
the necessary multimedia content before any costly activities
take place but to keep it in memory for as short a time as
Figure 1: Using paranormal radar to find ghosts
possible. A modular structure for game missions discussed
further provided the possibility to implement this approach.
Story Implementation. While location-awareness lends
itself well to immersion by placing the player in a physically
relevant context, a significant challenge remains with regard
to structuring the story content in a fashion that allows it
to be presented adaptively in response to changes in user
location as well as other modes of interaction. To address
this challenge, we have developed a flexible architecture that
allows non-linear stories to be expressed and presented as
part of a location-based gaming experience. The developed
mission infrastructure supports decomposition of the story
into atomic location-specific fragments and allows specifying
the relations between the individual fragments to ensure that
even a complex story with multiple narrative branches is
presented to the player in a meaningful way.
4. CONCLUSION
This paper has presented our experiences developing an
immersive location-based game running purely on a com-
mercially available smartphone platform. We described the
challenges of developing such a content-rich and feature-
rich application in a resource-constraint environment and
presented details on the way in which we dealt with these
challenges. To us, it is clear that the current generation of
smartphones is ready for a new class of games, but that they
still constitute a resource-constrained environment and that
care must be taken in addressing the associated challenges.
5. ACKNOWLEDGMENTS
We are grateful to the National Digital Research Centre
(NDRC) for funding the work described in this paper.
6. REFERENCES
[1] T. Carrigy, K. Naliuka, N. Paterson, and M. Haahr.
Viking Ghost Hunt: Design and evaluation of a
location-based mobile game. In Proc. of NordiCHI,
2010.
[2] G. H. Forman and J. Zahorjan. The challenges of
mobile computing. IEEE Computer, 27(4):38–47, 1994.
[3] N. Paterson, F. Conway, T. Carrigy, S. K. Jensen,
K. Naliuka, and M. Haahr. Implementation and
evaluation of audio for a location based augmented
reality game. In Proc. of ACM Fun and Games, 2010.
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