Now 64bit version is called openvr64pi.dll (patched the 64bit binary library openvr_api.lib) See also https://github.com/ValveSoftware/openvr/issues/412
OpenVR is an API and runtime that allows access to VR hardware from multiple vendors without requiring that applications have specific knowledge of the hardware they are targeting. This repository is an SDK that contains the API and samples. The runtime is under SteamVR in Tools on Steam. Documentation for the API is available in the wiki: https://github.com/ValveSoftware/openvr/wiki/API-Documentation More information on OpenVR and SteamVR can be found on http://steamvr.com