The goal of this thesis is to develop an interactive visual task for robot-assisted gait training after stroke. This is designed as a simple soccer-based computer video-game displayed on a screen, played by moving the ankle in dorsiflexion or plantarflexion to guide a soccer ball from its original position towards the goal. This stand-alone game is interfaced with the impedance controlled modular ankle exoskeleton ("Anklebot") that provides assistance only as-needed, as an augmentative tool to further enhance ankle neuro-motor control and whole-body function after task-oriented robot-assisted treadmill walking. The design and features of the interactive video game, as well as the underlying biomechanical model that relates patient-to-game performance are presented. Simple adaptive performance algorithms are embedded, and bench tested to auto-adjust game parameters in real-time, concomitant to ongoing patient performance during robot-assisted therapy. Human in-loop testing strategies are proposed to validate the video-game performance and its feasibility for clinical use.