Unity3d has been released for Ubuntu; see http://blogs.unity3d.com/2015/08/26/unity-comes-to-linux-experimental-build-now-available/ Any change for an ebuild in Gentoo?
I've begun the process of creating an ebuild for this which will wind up available via overlay once I'm finished. The binary released by their team is a simple makeself script which contains the tar. Of course if someone wants to put this into the real tree I'm supportive and would like to assist.
