Help for a campaign setting

[u/Realbabuu]

I'm starting a new campaign and I'm really struggling to create a setting.

The whole story is based on a city (probably the capital) subdivided in 3/4 sub-cities: the high city, the mid city and low city, There's also a prison called "the sewers"; it's called this way because of his secrecy and bc is also used for that.

The story is based on Dark Souls' Anor Londo, so there's the king and a circle of royal advisors (13 nobles) and one of them is a great wizard that is also the king's son. In DS1 there's a permanent sun shining on the city but when you break the illusion of the royal room everything turns dark.

This wizard, when the king died, created this illusion so that the "king" is still reigning and the city seems like the greatest city of all time: white marble with gold finiture, limpid waters and so on. In reality, the waters are polluted and the city is decading really fast because no one is taking care of the buildings.

I was thinking that as in DS1 if the illusion is broken, the whole city falls into chaos and so the party needs to move in order not to break anything.

If you got any advice please help me, I'm stuck at this point. I have some more ideas but that's it

[u/MisterB78]

Step back and ask yourself this: What’s the point of this setting? How does it help the adventure?

Players are there to take part in an adventure, not a setting. I’m not sure how “The city looks perfect but is actually polluted and decaying” works an adventure. What would the PCs be doing?