Do you see it rather as the guild city model i.e customisable constructions in a dedicated zone that require a very large effort to improve passably?
Do you see it rather as the social instance of the Serpent Inn in Khemi but that could be rented for longer periods with some customisations available?
Should it be constructed/purchased once for all? or rented periodically in order to spend Gold?
What features would be associated? bind point, extra storage, decorations, RP items, crafting bonuses when inside the zone? ...
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Personally i would like to see apartment rentals in the main cities, that would fit well into the existing settings: a few extra clickable doors, a concierge at the door to receive the payments (vet tokens or gold), a few instances that could highly benefit already existing content.
I do not like the ghost effect associated to dedicated zones deserted by players that stopped playing, and since these zones involve all new mechanics, there are often a lot of DEV charge and a lot of bugs associated.
The features would be basic such as extra storage, crafting bonuses (can't say much since i'm not in the course of what's in the craft revamp), etc. Some decoration slots could be added if some trophies were added to the game, though optional.
Option to rent from 3 'tiers':
T1 instance is single room, cheapest variant that can provide 1 extra storage and 1 feature to choose from the list.
T2 is a more comfortable condo, that provides 2 extra storages and 2 features to choose from.
T3 is for master housing comparable to the housing instances of Noble district that provides 3 extra storages and the full set of features.
Example of reusable content with minor tweaking:
T1: House of Kalanthes in tarantia, Serpent inn room in khemi, Tina's room in Tortage
T2: Guild cities 'underground' social instance
T3: Small Mansions of the Noble district, Palace of Yun Rau, ...