The game "Raiders of the Lost Treasure" was developed using Blender, an open source 3D content creation suite [14]. The use of this software package enabled us to create and manipulate three-dimensional contents, modelling, animation and rendering. The interactivity of the game engine was implemented in logical blocks and programmed using the computer language Python.
The models were constructed by combining and deforming the geometry of basic 3D objects, such as: circles, planes, cubes, spheres, cones, and cylinders. To change the appearance of a surface, the Vertex Paint feature was used, which allowed colours to be applied on the faces of the objects. The texture mapping was performed with the UVMap feature where a map of coordinates (UV coordinates), defines what should be applied on each side of the model. For the animation, the local structure of the bodies was modified to simulate surfaces that contract and stretch in response to external forces (skinning).
Defining type and characteristics of the game
The computer game "Raiders of the Lost Treasure" was developed to quantify the influence of colour stimuli on the performance of people with ADHD. An adventure game was chosen for being appropriate for children and adults.
Due to the low tolerance of the target audience in relation to failure, the game contains no time limit or virtual life losses. To make the game interesting for ADHD patients, the tasks are shorter and rewards are offered more often than those usually found in commercial adventure games.
The view mode chosen was the first person, so the player can see in more details the scenarios and their characteristics.
Sound hints to indicate the approach of important items were not implemented, making it possible to evaluate only the influence of colour stimuli, as recommended by American Psychological Association [15].
The game is sequential and the tasks follow a logical predefined order,, for example, entering the lake is allowed only after discovering the fishing net.
Story
Prior to beginning the game, an audio file with an introductory narrative runs and tells the story of an old pirate named Carlos who is interested in finding a lost treasure on a faraway island. When arriving at the island, he discovers that the treasure is located in an abandoned mine's room. To open this room, it is necessary to find a magic key, a mandala that was divided into four pieces, which were hidden in different places on the island. On the way, several coins are available; however, in order to get them it is necessary to avoid poisonous snakes.
Prior to starting the first task, an introductory help text is displayed giving information regarding relevant objects and hints necessary to achieve the goal of the game.
The game was divided into two levels and each level has nine tasks. The first level takes place outdoors, in an island, which favors the player to explore the scene quickly. The second level takes place inside a mine where more attention is needed to meet and overcome the challenges.
In the first level, the first two parts of the mandala are hidden in the island's fishing village and need to be found by the players. In order to help the players to accomplish the task, indication plates and procedure hints were inserted in the environment (Figure 1), as well as various animations were placed in the scenery for concentration and fun In the first level of the game, players would find the sceneries where tasks would be performed by either reading and interpreting the hints, or by exploring the scenery randomly. Even though the accomplishment of tasks is more time consuming when performed without the reading and understanding of the procedure hints, due to the characteristic impulsiveness, hyperactive players would cross the scene quickly, while other volunteers would follow the paths laid out by reading the information.
In the second level, hints help the player to find the two other parts of the mandala. When the search is completed and the mandala is put in place, the treasure room opens. This level was implemented to favour the players who are able to keep high levels of attention and who can remember the location of items placed at strategic points.
Versions of the game
To quantify the influence of colour perception on the performance of players, two versions of the game were implemented. In the first version, red-green colours are used to display important items in the game such as procedure hints (Figures 2a and 2b), as well as localization hints (information boards) and dialogue screens (Figures 3a and 3b).
In the second version, the colours of these items were changed to the blue-yellow.
Players' performance was evaluated by measuring the time spent to accomplish each task. Although no time limit was imposed to finish the game. Finishing it meant winning, while giving up meant loosing.
Software engineering
The logical structure of the game was developed using modular programming, which enabled us to reuse several routines during the implementation of the tasks. The scripts were written in a structured manner using the language Python. The software validation of the internal structure of the game was performed using a white box test and a functionality test was performed by a black box test [16].
The tasks are executed in a predefined logical sequential order. Access to the next task is only allowed after completing the previous task. The logical diagram (Figure 4) depicts the sequential task flow of both levels of the game. Initially, before starting the first task, the player has to choose the type of controls he wants to use, and the system then starts the audio narration conceptualising the game. After that the tasks sequence is started and the following sequence of tasks needs to be fulfilled:
Level one:
Task 1- Find the resident who knows the secrets of Treasure Island;
Task 2- Find the trunk where the first part of the mandala is located;
Task 3- Find the key that opens the trunk;
Task 4- Go back to the trunk and catch the first part of the mandala;
Task 5- Find the lake were the second part of the mandala is submerged;
Task 6- Find a fishing net to catch the second part of the mandala;
Task 7- Go back to the lake to catch the second part of the mandala;
Task 8- Locate the mine where the other parts of the mandala resides;
Task 9- Find the axe to break the fence that blocks the mine entrance;
Level two:
Task 10- Find the wizard who knows where the third part of the mandala is located;
Task 11- Find the place indicated by the wizard;
Task 12- Frighten the owl that guards the third part of the mandala;
Task 13- Find the wizard, who then requests the player to locate his lost ring in exchange for the fourth part of the mandala;
Task 14- Find the wizard's ring;
Task 15- Find a piece of meat to capture the tiger that guards the wizard's ring;
Task 16- Returns to the wizard and give him the ring to receive the fourth part of the mandala;
Task 17- Find the treasure room;
Task 18- Finally, insert the completed mandala into the hole on the wall close to the treasure room's door to unlock it.
Participants
The game developed in this study was approved by the local medical ethics committee. Experimental data was obtained from 17 men and 23 women aged 15 to 25 years old with moderate-to-good experience in computer games. The participants, all students, were selected by evaluating their computer skills through the execution of one introductory level of the commercial computer game "Prince of Persia" [17] with commands and characteristics similar to the game developed for this study. It was up to each user to define which commands to use: the mouse and keyboard, simultaneously or only the keyboard. From the 90 players who accomplished this test in 300 seconds ± 5%, 40 volunteers were recruited, consisting of 20 non-ADHD volunteers (A - control group) and 20 volunteers with ADHD, free of medications (B - experimental group). The classification for ADHD of the 90 volunteers was realized by a psychologist who analysed the data forms filled out by counsellors and teachers of the students, following the procedures of the Scale Adapted Disorder Attention Deficit/Hyperactivity Disorder test [18].
Groups A and B were subdivided into four subgroups of volunteers (A1, A2 and B1, B2). Subgroups A1 and B1 played the first version of the game with a predominance of green-red hints and subgroups A2 and B2 played the second version with predominance of blue/yellow for the objects.
Usability
The game is normally controlled using a mouse and a keyboard. A second option, selectable during the initialisation of the game, allows the game to be controlled by an alternate script using only a keyboard. In this case the screen pointer can be moved using the line-up, line-down, left and right keys available on a standard keyboard or through the assignment of user selected keys.
Data analysis
The performance of the players was measured, recording the elapsed time in seconds needed to perform each task. At the end of each task, a script stores the value in a variable and assigns 0 to the time counter initiating next task. At the end of the game these values, the name of the volunteer, as well as the day on which the test was performed, were stored in a log file.
The data analysis was performed using MatLab ®. First, Tmg, k was calculated, defined as the average time needed by the subgroup "g" to execute a task "k" and was obtained using equation (1) where Tg, v, k is the time needed by volunteer "v" of the subgroup "g" to complete task "k". As stated before, the volunteers "v" were divided in four subgroups "g", (A1, A2, B1 and B2) and the game consisted of 18 tasks "k", 9 in each level of the game.
(1)
The average execution time "TmF1g" needed by subgroup "g" to complete the first-level of the game (tasks 1 to 9) as well as the average time needed to complete the second-level "TmF2 g" (task 10 to 18), are calculated using equations (2) and (3).
(2)
(3)
The average time needed to complete the full game "Tmtg" for each subgroup "g" was calculated using equation (4);
(4)
The authors also calculated the total time needed to complete the first-level "TmtF1" by all four members of subgroup "g".
(5)
Similarly, the second-level total time "TmtF2" was calculated and obtained by the expression:
(6)
The obtained results were analysed with the D'Agostino's test to prove that the distribution was normal. The Two-way ANOVA test was used to detect if significant difference exists between subgroups and the posthoc Tukey - LSD (least significant difference) test was used to define which subgroup was different from the remaining subgroups.