License restricts how others can use your world to build their worlds.
You can release the world under saint, knight or hermit license. All licenses are only effective inside the realm of World_Gate. The author holds full rights outside World_Gate.
Saint
Saint license means that anyone can acquire, distribute, run and directly use part or all of this work for other projects without any restriction. Giving credit is not necessary but appreciated.
Knight
Knight license means that anyone can acquire, distribute and run this work without any restriction. Directly using part or all of this work for other projects requires appropriate attribution.
Hermit
Hermit license means that anyone can acquire, distribute and run this work without any restriction. Directly using part or all of this work for other projects requires explicit permission from the author.
Note that building an expansion is not restricted by this license because expansion does not directly use base world.