openvr : 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. ( https://github.com/ValveSoftware/openvr )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a kzd
For Paludis use this rsync : rsync://gentoo.zugaina.org/kzd-portage
If you have a problem : ycarus(-at-)zugaina.org