A fictional archipelago, located
Scientists and engineers working on technology that would ultimately yield the NTSC (colloquial backronym No-Time Space-Change) Drive accidentally trigger a castastrophic event. A pinpoint spherical void, from which no light or matter emerged - travelling roughly (x degrees) north-west and near tangential to the surface plane at roughly walking pace, and very slowly expanding. Anything it touched and passed through was simply removed.
The black sphere anomaly
Thirty years later, the rate of expansion is greater than it's velocity, and the outer surface of the sphere is approaching its origin.
The exact cause and nature of the effect is unknown.
People treat it much the same as climate change - it's too big to do anything about. The development of the NTSC drive made space exploration and colonisation achievable, a new frontier. So people aren't really afraid of Earth territory being devoured by the sphere.
The archipelago is past its economic peak. Old and new are layered and mixed through each other. Signs and advertisements in the archipelago are a mix of English, Japanese and Umaphrān.
Hovering vehicles are common - small utes and bikes especially, and a good levitating train system.
Food is mostly vegetarian, with the exception of one main city.
Local religion has thousands of gods and demons - often hyperlocal, and acknowledged with small shrines but no large worship centres.
Television is rare as the people prefer radio.
Towns are crowded and nested with buildings.
It appears to be a language isolate. Conspiracy theories exist that the archipelago is somehow out of time and was introduced (like the Mandela effect) when the black sphere incident occured.
NTSC research centre
The research facility has been converted into a sort of museum/research facility. The initial site has been preserved - you can actually go and see the 'bullet holes' created by the anomaly behind glass. The facility itself is in the archipelago's north, now constantly cold and snowy caused by the sphere.
The player character works repairing 3D projection devices - a sort of 3D vista, like the looking glass technology in Prey.
He runs his own business. He is also past his prime.
He has a little workshop with enough room for his キュート below and a house space above.
Divided into levels - alternating gameplay and just exploration/conversation. The gameplay levels also involve some conversation and exploration.
The player troubleshoots and repairs the projection devices in the gameplay levels.If this is too complex, perhaps the player could be tasked with cleaning graffiti.
In the conversation levels we learn more about his life - e.g. he visits his favourite izakaya often, or catches up with a friend, or tidies his workshop.