Create a VR Town in unity (similar to OpenWonderland)

Hi,

I just discovered unity.
I wonder if it is possible to create a Virtual World - a town or street visitable by several users at the same time as avatars. The user shall see eachother, talk and walk together through the 3d environment of the town.
This scenario requires a dedicated server on the Web and clients each user must install, run as an application or embedded in a Web browser.

The Virtual World must be about 0.5x2 km and be able to carry about 10-50 visitors (avatars).

I wonder if this is implementable in unity i.e. similar to http://openwonderland.org/

If that is possible, what kind of licence unity would be suitable?

Thank you!

Possible yes , easy … not at all.
The pro version has its benefits for optimization and some other things but the basic concept should be doable in the free version.