The Rehality consortium aimed to accelerate and sustain stroke rehabilitation by providing patients with a digital therapy that combines software‑based virtual reality (VR) environments and gamification elements. From the patients’ perspective, the central goal was to deliver a sense of success when completing therapeutically necessary tasks while allowing exercises to be performed independently, without the need for extensive clinical infrastructure or constant therapist supervision. In the long term, the project sought to bridge the gap between acute inpatient care, formal rehabilitation, and home‑based therapy, thereby hastening patients’ return to independent living. The VTplus contribution focused on building a demonstrator that enables rehabilitation exercises in VR with a closed‑loop control system driven by real‑time brain and muscle signals.

VTplus GmbH, a specialist in VR systems and laboratory equipment for psychology, psychiatry, neurology, and rehabilitation, supplied evaluated VR scenarios, virtual characters, and expertise in integrating biosignal interfaces and gamification. The consortium also included the University Hospital Tübingen, providing clinical brain‑research and neurological expertise, and the Hochschule der Medien – Institut für Games in Stuttgart, contributing knowledge in interactive media, serious games, and VR. The project was funded under the NKBF 2017 program (grant number 13GW0213D) and spanned from early 2021 to mid‑2023.

In close collaboration with the University Hospital Tübingen and the Institute for Games, VTplus designed a system concept that adhered to human‑use standards and produced a comprehensive software and system architecture. The architecture defined system functions, components, and communication structures, with a specific focus on the upper body—arms and hands—critical for stroke recovery. A fully integrated VR system with a closed‑loop hardware interface was specified, and sensor technology for capturing behavioral data was selected based on a user analysis. Eye‑movement tracking was implemented as an indicator for movement initiation and tested within a puzzle application. A direct interface between the biosensor hardware and the VR engine was developed, using the Lab Streaming Layer (LSL) protocol for real‑time data exchange. To support testing and control, additional methods were created to simulate expected biosignal data.

The closed‑loop feedback module and therapy scenarios were iteratively developed and evaluated. Partial solutions from VTplus and the Institute for Games were merged through a shared Unreal Engine 4 project, with version control enabling parallel development. The system architecture was refined during a virtual workshop on 21 January 2021 and further optimized at a consortium meeting on 19 August 2021, where interfaces for sensor integration and a neurofeedback component were added. The final demonstrator allows therapists to trigger specific exercise steps in real time based on detected neural and muscular activity, providing immediate feedback to the patient and enabling adaptive training protocols.

Overall, the technical outcome is a validated VR rehabilitation platform that couples closed‑loop biosignal monitoring with gamified exercise modules, ready for clinical evaluation. The collaboration among a VR technology provider, a clinical neurology center, and an interactive media institute ensured that the system meets both scientific rigor and practical usability, positioning it as a promising tool to close the continuum of care for stroke patients.