Hey Mayors,

Today Lobby sent me some more info about the plugin system.
It will probably be included in some of the next updates.

Some info, from Lobby's message:

Players will be able to create their own buildings using JSON files.
You can create residential, commercial and industrial buildings.
They have to be saved in TheoTown/plugins.
You will be able to share your plugins with others.
Game will use a 1024x1024 picture to store the plugin buildings, so don't make too much of them or don't make them too big. It should run a few hundreds of normal-size buildings, but it depends.

Sounds interesting, can't wait for it. If you want to start creating plugins, a tutorial will appear on this forum, when the feature will be added.