Unity3D is a 3D gaming engine and suite of tools for RAD game development. Unity3D editor is cross platform (MacOSX, Linux, Windows), and can build for a number of targets including aforementioned platforms and iOS and Android. Unity does not provide us with any RPMs or repos to get this quickly up and running under, but can be made to run with little hassle.
GET MONO & MONODEVELOP INSTALLED
1. Install mono repo by issuing the following 3 commands:
yum install yum-utils rpm --import "http://keyserver.ubuntu.com/pks/lookup?op=get&search=0x3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF" yum-config-manager --add-repo http://download.mono-project.com/repo/centos/
Install mono & monodevelop:
yum install mono-complete monodevelop
Create libs symlink to take into account the way EL and Fedora handle lib32/lib64 separation is not recognized in Unity3D:
ln -s /usr/lib64/libMonoPosixHelper.so /usr/lib
DOWLOAD AND EXTRACT UNITY3D
Install npm if not present:
yum install npm
Download and extract unity. We are looking for the .sh version.: http://forum.unity3d.com/threads/unity-on-linux-release-notes-and-known-issues.350256/
It is up to you if you wish to move the folder somewhere else. I personally moved it to be /opt/Unity/. I then copied and fixed the .desktop links that are there into ~/.local/share/applications/. When fixing the .desktop entries, the proper category to make these show up in "Programming" is actually only going to work if you set the category to be Development. Sigh...
Test things out by running /PATH_TO_FOLDER/Editor/Unity or via the .desktop file's menu entry. You should have it open up and show something. The only dependency I was missing for functionality was npm, let me know if there are others not in the list above. In the meantime until I can get the full list of packages generated so one can use a one-shot command, refer to the download page linked for the compete list of Debian/Ubuntu dependencies and adjust as needed. Its a long one ...
Also test out to make sure MonoDevelop works by issuing the command monodevelop or by using the menu link (Applications -> Programming -> MonoDevelop)