Worldstone is an active work in progress. Without revealing specifics, my development process began by answering some worldbuilding questions: how did the world come to be like it is? What mechanics or gameplay loops will be required and what does that require the world to be or have? What is special or different from the way things work in the real world?
Next, I looked at it from a player's perspective. Who are they, and who is the character they play? What do they need to know at the start, and what can they do? What's their place in the world, and more importantly, what don't they know but need to discover in gameplay? What future surprises, revolutions, and cataclysms might they experience—or bring about—based on their choices given all of the previous information?
Finally, I used Stable Diffusion to quickly generate images, one of which ("The Artifact") I then created in Blender as more presentation-level concept art. I wrote a script for the game intro as a way of quickly bringing together the key elements of the setting, the mood, the character's knowledge needs, and appropriate visuals together into a single piece.
"It's off, somehow. Odd. It's not just a stone, despite its rather prosaic appearance. You wouldn't give it a second glance here in the field, but you may have noticed something as we approach it: a shift in the light, or the sensation of your ears becoming plugged. Or perhaps such things merely tickle the back of your mind, making you feel somewhat distracted. It is certainly not the poppycock that the constable described, but it is what we are here to study!"