kae, rok temu

That’s not how this works.

You’re free to create stories, video, of your own video game in the universe. If you chose to make that public domain and give it away for free, then good on you.

Others can create freely in this universe with their own expression, which they could charge for.

Much like how there are movies about Cinderella or Red Riding Hood which are under copyright, but the base story itself is in the public domain and free to use.