Do you want to use SteamVR (OpenVR) and use OpenVR features like custom OpenVR Overlay applications inside Bigscreen? If you have a SteamVR headset like the HTC Vive, Bigscreen will automatically open with SteamVR.
But if you have an Oculus Rift, Bigscreen will automatically use the native Oculus SDK (higher performance). If you want to instead force Bigscreen to open with SteamVR, follow these steps:
-vrmode openvrand hit OK.