Pioneers of Plymouth is a Settlers of Catan game clone which was made to be free, open-source, and server-based. It was made as existing Settlers of Catan video games are not stable.
There is no license, as I doubt it can be licensed at all. Use and modify it how you please, you can always contact me from my profile or keybase. I will try to make the setup of your own instance of Pioneers of Plymouth as simple as possible. This does use a modified version of zbee/UserSystem which is licensed under GPLv3.
Please read the installation document if you want to spin up your own instance. I want to also switch my systems over to Heroku, and then offer a Heroku button to instantly spin up an instance.