## 5 The Eye-Hand Coordination Game
### Evaluation Mode  
In the evaluation mode, eye-hand coordination is estimated based on different parameters derived from the performance of drawing tasks. For this purpose, the gameplay promotes the use of paths (labyrinths) where a ball must be driven from the start point to the final point. This gameplay is simple, but it requires good eye-hand coordination to carry the ball from the green circle (start point) to the red circle (final point) while minimising the expended time and avoiding going outside the central path. Figure 5(a) presents the virtual scene for a path. The red circle indicates the point from which the ball begins to move. The red circle is the target point. In the middle of the path, there is a white line that indicates the \"ideal\" trajectory (equal distance from the side walls). When the ball collides with the side walls, a prompt message (cloud-like) appears to notify the user to correct the trajectory. Additionally, several \"coins\" are distributed along the ideal trajectory. Each reached coin gives a point. Finally, the game time and score are displayed in a panel in the upper-left corner. The scores are determined by the coins gathered by the user. Figure 5: Initial menus in the eye–hand coordination game. Figure 6: Environment for eye–hand coordination assessment. Figure 5(b) presents the full set of virtual environments implemented in this game based on the system described in [17]. The patterns were designed by therapists at a handwriting clinic and categorised into three main classes: Straight-to-Curvy, Complex, and Width designs. Complex patterns are longer and more demanding to follow. Straight-to-Curvy patterns involve transitions from straight lines to curvy lines. Finally, width patterns increase their level of difficulty by making the path narrower. In addition to the different path designs, the assessment scene allows configuring each path according to the patient's characteristics. Figure 7 presents the settings screens for the evaluation mode. The main options are as follows:  
* Normal Options:
* Size: Using a slider, this option allows the user to scale the path size proportionally. * Game mode: This option allows choosing between simple and awarded (coins) paths. * Advanced options:
* Ball size: Three ball sizes are available to change the accuracy level. * Path tolerance: This advanced option controls the threshold to activate the audio and visual warnings related to the tolerance for the ball going outside the path. Three levels are available: low (a message appears when the ball goes outside the path), medium (a message appears when half the ball is outside the path), and high (a message appears when the ball touches the walls). Evaluation Mode with Robotic Devices  
The video game is designed to run in desktop or tablet mode. That is, the mouse or stylus pen can be used as an input device to control the ball motion. Due to the nature of these input devices, feedback other than sound or visual prompts cannot be provided. However, in the evaluation mode with assistance, the goal is to use a device that provides haptic feedback to the user, rather than just capturing the hand position, like the mouse or stylus pen. According to the results in [17], the haptic effect helped make the traces more accurate, faster, and smoother. Figure 8 illustrates the assistance mode using the Phantom Omni robot. As previously mentioned, this device transmits its end-effector pose to the virtual environment via the _OpenHaptics_ library. In the virtual scene, there is a virtual sphere (green circle with dashed line) attributed to the haptic device's end-effector, which is attached to the player ball (blue  
Figure 7: Additional scenes in evaluation mode. circle). Inside the path, the player ball and the virtual sphere (corresponding to the robot's TCP) are aligned, so no haptic effect is active.