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University "Pierre et Marie Curie" - Inserm U483
9, quai Saint Bernard
Paris, France 75005
The TiM game engine is dedicated to the development of games specifically designed for visually impaired children. It was created within the framework of The TiM Project  (Tactile Interactive Multimedia Games for visually impaired children), funded by the European Commission.
Various games from different categories were designed using this platform. In this paper we will explain first the requirements that conducted the development of the TiM game engine, then we will describe several of the TiM games.
Prior to the start of this development, a preliminary study showed that partially sighted children who had enough visual perception to access mainstream games would not use specific games. Therefore we concentrated our efforts on children who cannot use the ordinary graphical interface because they are totally blind or because their partial sight is very low (<0.05), with or without additional disabilities (slight to moderate). Their ages vary from 3 to 10 years old.
The platform allows to design games that may be adaptable to the visual possibilities of each child, using various devices like: tactile boards, braille displays and keyboards, speech synthesisers, surround audio system, customisable graphical displays (scalable font prints, adjustable colours and contrast...); but also standard devices as speakers, keyboards, mouses, joysticks... There is always a nice graphical interface that is useful to the sighted (parents or peers for instance).
One big constraint was that the games are really games. It seems obvious, but it implies that those games would be very easy to use, and then it was impossible to use standard access technology like screen readers. Indeed those tools allow to do very complex operations with mainstream program, but are very difficult to use. Then the TiM game engine is able to drive directly any kind of specific device.
2. The TiM game engine: Technical summary
The TiM game engine  has a multi-layered architecture, which main layers are: the Platform API and Low level modules.
The low level modules are external libraries used by the platform internals to manage each kind of device. The architecture allows to easily update those modules or add a new one corresponding to a new kind of device. We designed specific libraries to access to Braille and tactile board devices (respectively libbraille  and libboard), independently of models and manufacturers. We use the Open Audio Library (OpenAL - http://www.openal.org) for playing sounds in standard stereo as well as 5.1 surround system of speakers (OpenAL is a joint effort to create an open, vendor-neutral, cross-platform API for interactive, primarily spatialised audio); and we use Simple DirectMedia Layer (SDL - http://libsdl.org) for the low level interaction of the platform with keyboard, mouse and screen (SDL is a cross-platform multimedia library designed to provide fast access to the graphic frame-buffer, audio devices, keyboards and joysticks).
The platform API is organised in many different components. Those components have preexisting functionalities that are provided to the game designer to simplify game design. Given TiM objective of adaptive games, components are very high level objects completely independent of the game representation. The scenario will manipulate only abstract objects, while the data corresponding to each modality are stored in an XML style sheet. The scenario is usually written using the Python programming language.
To give a simple example, the API contains a component 'button'. In the scenario a button is used through an ID. It is possible to create it, to show it, to hide it, to delete it, and to attach an function to do when this button is activated. Then the data corresponding to the graphical description of the button (picture, position...), to its textual content, to its alternative content for Braille, the keyboard shortcut, the different languages, etc... are stored in the style sheet.
The system will decide what data to send to what device according to the devices used by the user, to the language. The game programmer don't have to know anything about software communication with Braille devices for instance.
3. TiM Games
3.1 Reader rabbit's: Toddler
'Reader rabbit's: Toddler' is an adaptation of a mainstream discovery game designed for children from 2 to 4 years old. The child discovers, helped by animals and by music, 9 animated educational games. 6 of these activities were adapted to be used with keyboard and tactile boards (on which tactile sheets with different material, fabrics, leather, Braille labels are sticked).
In one of these games, the user has to find the mother of animals (listening to their voices); in another, he can put together different musical elements to make his own sound...
'MudSplat' is an arcade like game where the player defeats mud throwing monsters by squirting water at them. The player can hear the monsters appearing on a line in front of him; he/she estimates their position (thanks to stereo pan) and has the possibility to move left or right (with keyboard or gamepad); then when he/she thinks a monster is in front of him, he can shoot with a water hose: the monster, who don't like to be clean, disappears. The monsters can also fire throwing mud (if hit, the player will loose one life).
After having defeated a certain number of monsters, the player will reach the next level. 25 levels of increasing difficulty allow skilled player to play for a long time, while beginners can still have fun on easy levels. The main traditional features of arcade games were implemented (like extra lives, levels, bonus objects, bonus levels). A high score list is maintained where the player may insert his name.
'X-tune' is a musical construction game where the player can sequence and play with different sound environments (called 'patches'). A patch consists of 15 sounds from a theme. The player creates music by combining sounds, and by manipulating them (volume, tempo, pan position, sound effects) and arranging them in rhythmical patterns. In X-tune the child simply creates music, using, as he/she likes, sample d instruments or recorder sounds, that he/she may record himself (like "everyday sounds").
3.4 TiM Magic dictation
'TiM's Magic dictation' proposes an implementation, based on the TiM technology, of popular toys that can be found in mainstream toy shops. These toys look like computers and implement lots of activities like find a letter, spell a word, hangman, etc. The level of difficulty increases with the targeted age group, and the kind of activities also varies a lot. The screen of these devices is usually of very low quality and very difficult to use by children with low vision. Obviously they cannot be used at all by blind children. Then the TiM Magic Dictation enables Blind and severely visually impaired children to access this kind of games.
4. To conclude
Several other games are currently under development, like 'Tim's journey': an exploration game where the player solves a mystery in real-time, by exploring a surround sound environment; or a discovery game for the youngest where the child makes an association between sounds and tactile elements.
The next step of the project is to build software tools simplifying the creation of game without any programming skill. The idea is to design templates of games allowing to personalize an existing scenario, by including in it his own resources (sounds, pictures, texts...).
More information at: http://inova.snv.jussieu.fr/tim/
The presentation will let a large part to demonstration of the games.
The TiM project is funded by the European Commission, on the program IST 2000 (FP5 - IST - Systems and Services for the Citizen/Persons with special needs) under the reference IST-2000-25298. The contents of this paper is the sole responsibility of the authors and in no way represents the views of the European Commission or its services. The TiM project participants include: Inserm U483/INOVA from Université Pierre and Marie Curie, coordinator, (France), Les Doigts Qui Rêven t (France), Université du Havre (France), Association BrailleNet (France), Royal Institute of Technology in Stockholm (Sweden), Sunderland University (United Kingdom), The Swedish Institute for Special Needs Education (Sweden) and Virtua Ltd (UnitedKingdom).
We thank the company 'Mindscape' for allowing the adaptation of the game "Reader rabbit's : Toddler".
 Archambault D., Burger D., and Sablé S., The TiM Project: Tactile Interactive Multimedia computer games for blind and visually impaired children, in Assistive Technology -- Added Value to the Quality of Life, In: Marincek C., Bühler C., Knops H., and Andrich R. (eds.), Proceedings of the AAATE'01 Conference, Ljubljana, Slovenia. September 2001, IOS Press Amsterdam, The Netherlands, pp. 359--363
 Archambault D. and Sablé S., A Game Engine for Designing Adapted Computer Games for Visually Imapired Children, in CSUN 2003, Technology And Persons With Disabilities Conference 2003, Los Angeles, March 2003. http://www.csun.edu/cod/conf/2003/proceedings/191.htm
 Sablé S. and Archambault D. libbraille: a portable library to easily access Braille displays. Proceedings of ICCHP 2002, 8th International Conference Computer Helping People with Special Needs. Linz Austria July 2002. Springer, LNCS 2398, pp. 345--352. http://libbraille.sourceforge.net
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