These ebuilds come from http://git.overlays.gentoo.org/gitweb/?p=dev/nirbheek.git.
If you have some problems, go to the official site first.
penumbra-overture-bin : A first-person survival-horror adventure game ( http://www.penumbra-overture.com/ )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a nirbheek
For Paludis use this rsync : rsync://gentoo.zugaina.org/nirbheek-portage
If you have a problem : ycarus(-at-)zugaina.org