English - With 'ICAORSmulti' we present a cooperative Virtual Reality application that was developed for the presentation and validation of multimodal interaction techniques. To have an application scenario at our disposal that is attractive and can be demonstrated at trade shows, we chose a flying-based virtual environment for multiple users. The latter are able to interact and assume different roles. As input devices, we use up to two ICAROS flying machines that were specially designed to simulate a flight in VR. The users can move and navigate through the VR environment in a horizontal position (see figure 1). By means of a head-mounted display (HMD) they can see their virtual surroundings, while the sensor technology attached to the Icaros detects and communicates their movements. Actuator devices such as wind machines, heat lamps and others enable a multimodal output and improve the immersion of the flight simulation. Beyond that, it is also possible to integrate other devices and 3D interaction techniques such as running, climbing etc. into the current scene. All users are able to see each other and to communicate. For the simple development and testing of 3D interaction techniques based on predefined templates in Unity3D, several different components have already been developed and integrated. They are briefly described in this paper and can be tried out in a demonstration at the conference 'Mensch und Computer 2019'. One of the unique features of this project are components that perceive a measurable decline in immersion, e.g. a limitation of the viewing area, the latency or the frame rate.