To expand further:
The development philosophy could be though of as a big mixing bowl that everyone can add, remove, or improve ingredients. It is entirely possible that a complete mess could result, but it is also possible that something decent could come from cooperation.
To organize such a project, public discord channels could exits for each element of development like programming, quests, or environment designing.
To keep track of data, publicly editable google docs could be used. A master design doc would outline the major design decisions, a quest guide could outline all of the quests with possible outcomes, and spreadsheets for balancing characters and items.
The whole project would be "Unlicensed", which puts it into the public domain, so everyone equally owns it. People can still take credit for the work they have done, and it would still be proper etiquette to ask permission before modifying someone else's work.
Open Project Repository: Anyone can download the project files and open with Unity 5.6.1f1, and anyone can directly contribute.
