Unending has hidden tools for creating its puzzle campaign.

Edit Mode can be toggled by pressing Ctrl + Alt + E on the title screen.

Editing the campaign requires a keyboard and mouse.

When you enter the game you can now press P to edit the level.

The edited campaign map is separate from the one in the game.

There is currently no feature for loading a collection of map-worlds, they are normally installed by hand. Sharing is limited to map.pngs of individual levels, or changing the contents of the worlds data folder and using edit mode to access it.

(If someone goes to these lengths to share their own puzzle campaign then we can discuss how to improve this process.)