Running Unity Web Player on Linux using Pipelight
Officially Unity Technologies only support creating executable standalone games/3D applications which can then be run on Linux. This is done by using the Unity Editor in Microsoft Windows and OS X operating systems. Unity Technologies do not provide a Linux version of the Unity Editor, nor the Unity Web Player. Unity Web Player can still be run on Linux versions of Mozilla Firefox and Google Chrome by using Pipelight. "Pipelight is a special browser plugin which allows one to use Windows only plugins inside Linux browsers."
Developers and contributors to the Pipelight project have added a plugin for running the Unity Web Player. Instructions on how to install and enable the plugin are listed in their Pipelight installation instructions. Pipelight and Unity Web Player plugin installation page - http://fds-team.de/cms/pipelight-installation.html