Bootle Blast: A Movement Tracking, Mixed Reality Video Game
GamePlay
Bootle Blast tells the story of Botley the robot — a painter turned inventor — who invents a replicator machine to create Bootle Bots that assist him with his paintings. The machine malfunctions, unleashing a swarm of mischievous Bootles across Sky Spark City. Tasked with restoring order, the player’s mission is to locate and collect the rogue Bootles!
The game is structured around a series of movement-driven mini-games. Players engage in targeted motor tasks, referred to as "power moves," to capture the Bootles while simultaneously collecting in-game rewards such as coins and gear. Bootle Blast currently includes 13 mini-games, each designed to reinforce specific movement patterns essential for motor skill development. The game systematically targets finger dexterity (manipulation), grasp and release, wrist pronation/supination, shoulder abductionand flexion, elbow extension, trunk lean, cross-body reach, and bringing hands to midline. 5 of the mini-games integrate mixed reality elements, requiring players to grasp, manipulate, and release physical objects as part of gameplay. This mixed-reality approach bridges fine and gross motor skill development, offering enhanced task specificity and functional skill transfer to everyday activities.
A key feature of Bootle Blast is its dynamic difficulty scaling, which adjusts in real time as players practice and progress through different skill levels. This adaptive mechanism ensures that movement challenges remain appropriately graded, optimizing motor learning through progressively complex tasks.
These activities are designed to support individual play, while select mini-games offer competitive and cooperative multiplayer modes, fostering both independent skill development and social play interactions. Bootle Blast’s game mechanics are rooted in motor learning principles, leveraging interactive computer play (ICP) to provide an engaging and adaptive environment for motor skill acquisition.
Hardware
Bootle Blast uses a 3D camera-computer (Orbbec Persee) and body tracking software to capture the positions of 19 body joints/points from which rich kinematic data is derived to measure and track changes in function over time. The device is simply connected to a display monitor or television screen using a common HDMI cable, much like commercial game consoles.
Gross motor movements are tracked via relative positions of body segments and/or joints. For example, an elbow extension/flexion is measured as the interior angle formed between the shoulder, elbow and wrist. Fine motor movements are tracked using a combination of skeletal tracking via the 3D camera and object tracking via the RGB camera integrated into the sensor. This two-pronged approach is necessary as skeletal tracking of the wrist/fingers using 3D cameras is unreliable, particularly for individuals who may not have typical range of movement.
To address this technological limitation, we introduced coloured objects (e.g. building blocks). Tracking these objects in conjunction with the hand enables us to register important therapeutic movements such as forearm supination and grasp/release of objects while introducing physical task parameters that are important for supporting functional gains. Bootle Blast is unique in its use of mixed reality to support fine motor skills development in both pediatric and adult therapy systems. The Bootle Blast software is built using Unity, a cross-platform game engine.
Rehabilitative Measures and Kinematic Analysis
Data captured by the 3D motion tracking system, along with game scores, can provide insights on children's dissociated movements (i.e. isolated movement and movement pattern; e.g. functional reach) and coordination (i.e. the smooth and controlled use of movements in motor performance with consideration of timing, velocity, targeting accuracy, motor planning, directions, force and endurance; e.g. grasp and release).
Rehabilitation activities practiced in Bootle Blast are quantified as follows:
- Frequency/Intensity. Bootle Blast tracks every second of game play, differentiating between passive (e.g. navigating menus) and active (e.g. practicing rehabilitation exercises) from which intensity and frequency of rehabilitation activities can be precisely quantified. Active play time is presented to the player through the game interface (i.e. the mission time clock).
- Repetitions. Kinematic analysis of joint data enables calculation and logging of repetition counts for individual movements (e.g. elbow flexions) beyond individualized thresholds (e.g. 80% of maximum) for each joint during gameplay.
- Movement patterns. Kinematic analysis of joint data, in conjunction with object tracking for mixed reality games, also enables quantification of goal-oriented movement patterns (e.g. shoulder abduction + sustained hold on target). Achievement of movement patterns is logged and presented to the player through game scores.
