When a person is in a coma or in a situation where they are unconscious with a large group of people, they go to the borderland. The borderland, also sometimes called Underland, Wonderland, or the land of games is a place where people between life and death are sent to play death games. Because the thetan is considered foreign to the borderland, they have a visa that must be extended by winning games, with those losing being eliminated and dying. Upon clearing enough games, every person is given the option to return to the land of the living or stay and become a citizen of the world, not needing to do anything to survive but usually designing the games that are played in the borderland as well as having a say in its design which changes every cycle.
The Borderland does not have a consistent design because it is an arena. What is usually done is that six cities are chosen for its design, and the downtown areas of the chosen cities are made into a kind of theme park for the next cycle of players that will participate. It must be walkable since there won’t be cars and even the subways are unlikely to work or be useful to most of the people participating since the tunnels will have activities hosted inside of them. Some arenas are based off of cities in the underworld, the celestial bureaucracy, or even cities deeper in the astral planes. Some are even made by artists or reflect natural environments in different directions (Though this is uncommon and usually buildings are added for playability).
Baron Blackjack and Maman Meche are able to help any person who finds themselves in the borderland, and any person in a coma should be given lucky items such as dice, cards, poker chips, or anything else that will make it easier for them to complete any games. It is theoretically possible to escape the borderland but the baron tells me this just results in people becoming ghosts and has the same effect as losing, with many unable to cling to the land of the living long enough to return to their physical bodies. However, the borderland is only there for those who completed their set lifetimes and have a strong desire to stay past their agreed date of exit.
Borderland citizens or Borderlanders are not usually the most sane of spirits because being around constant death games takes a toll on their sanity, and many choose to pass on soon after becoming citizens. The ones who enjoy it and stay longer are the ones who take death less seriously and see it as a form of just losing a game or being eliminated from a competition.