A fictional setting of uncertain applicability.
Suppose you step through a magical portal of some kind and find yourself in a some sort of featureless beige nowhere. You can see yourself just fine, and there is visibly ground of some sort because you have one of those vague shadows that you get on overcast days. You jump about and find gravity works as you’d expect, and when you toss a grocery store rewards card in lands on the same ground you stand on, but there is no other visual evidence the ground exists. Everywhere you look is a uniform featureless beige.
Not knowing what else to do, you set out walking, mostly at random, but after some time you notice a blip somewhat above the horizon. Curious, you walk toward it until you are right beneath it and, looking up, discover that it is another person, seemingly standing on the beige ground as are you, but above your head and angled in such a way as to indicate a contradictory gravity. As you mind registers this fact you experience an uncomfortable lurching sensation and then find yourself subject to the gravity and, uncomfortably after you fall “up” to it, ground of the other person.
As you converse with this person and continue to explore the land you discover that it always has a single orientation and ground in the mind of each person and that when people meet their views coalesce. When their gravities agree this can be as painless as perceiving a hill or cliff separating them, but when their gravities are incompatible at least one experiences a sudden shift to bring about agreement.
“There are some people,” explains this unexpected guide, “who are so unobservant or pigheaded that they can walk through a village sideways and make the whole village—people, livestock, houses, everything— crash to their unique sense of down.”
As you continue to explore you discover there are indeed settlements, though they seem fairly wide-spread. “Anything everyone forgets about vanishes,” remarks on old-timer. “A great journal-keeper demonstrated this beyond doubt when a significant portion of items he had recorded placing in specific locations were found to be missing.” Roads neatly lined in cut stone (“you can find anything under the beige when you dig. Rock, ore, coal, water—the things you’d expect.”) tend to have their individual stones forgotten, turning into roads with vaguely defined lumpy borders. These likewise become less distinct in people’s minds until they vanish altogether.
Welcome to a Smooth Beige World.