Not long ago, the Unity game engine has received native support for Linux, permitting the users to create apps and export them to other platforms.
For now, Unity 5.1.0f3 Game Engine has been released, but it’s just an experimental version to created for 64 bit Ubuntu systems, but depending on its adoption rates, more versions may be released for the penguin.
To install the Unity 5.1.0f3 Game Engine on 64 bit Ubuntu systems and derivatives, like Linux Mint, Pinguy OS, Elementary OS, Deepin, Peppermint, LXLE and Linux Lite, you need to download the deb package from the projects website and install the via command-line:
$ sudo apt-get install gdebi
$ wget http://download.unity3d.com/download_unity/unity-editor-5.1.0f3+2015082501_amd64.deb
$ sudo gdebi unity-editor-5.1.0f3+2015082501_amd64.deb
Optional, to remove unity editor, do:
$ sudo apt-get remove unity-editor*