A lot of the work could be mitigated by using an already established opensource client.
One example would be "Ryzom"
http://www.ryzomcore.org/ One of the interesting things they did was release ALL of their games assets under the CC license.
Worldforge is another one...
http://www.worldforge.org/
I mean don't reinvent the wheel guys.
I'll also say that I think there are some issues with unity and linux. The main one that comes to mind (I could be wrong) is that development can't be done on linux you can only target binaries for linux.