In Doomsday City, newcomers could establish their own safe houses step by step according to the system prompts. Even if an alliance expands in the future, as long as they didn't oppose the alliance and chose to join, their safe houses would still be protected by the system.
However, in a city like the City of Sin, wanting to own a property required a significant investment. If you wanted to live more comfortably in a larger house, you would need to possess a noble rank within the city.
Ordinary players in such cities could only rent homes designated for civilians, and these were quite expensive. Moreover, the monsters surrounding the city were regularly cleared out by the city guard forces, and those who wanted to level up by fighting monsters had to travel far and engage in combat with higher-level monsters. This setting was in stark contrast with Doomsday City, so it wasn't impossible for some players to choose to return to the latter.
