The new Dungeons & Dragons Open Gaming License, a document which allows a vast group of independent publishers to use the basic game rules created by D&D owner Wizards of the Coast, significantly restricts the kind of content allowed and requires anyone making money under the license to report their products to Wizards of the Coast directly.
https://gizmodo.com/dnd-wizards-of-the-coast-ogl-1-1-open-gaming-license-1849950634