We are using multiple commercial graphic engines (Unity, Unreal) to facilitate the development of Virtual Reality experiments for our different hardware setups.
We primarily use the Unity game engine from Unity Technologies for development and deployment of our experiments. With the help of the commercial middleware solution MiddleVR from I'm in VR, we are able to run Unity based experiments in all of our VR labs. We are able to transition existing Unity experiments with relatively small effort from one VR setup to another. One example would be a HMD based experiment which will later be run in the PanoLab cluster-rendering setup. Unreal Engine 4 (UE4) is used as an alternative when high-visual fidelity is needed such as helicopter and driving simulation visuals. We have extended UE4 with VRPN tracking capabilities, which allow us to run UE4 in a mobile VR setup in our large tracking hall. A custom UDP plugin allows it to be used with our motion simulators like the CableRobot Simulator or CyberPod.
The discontinued Virtools software from Dassault Systèmes is no longer used for new experiments.