Shahnameh
The Book of Kings. Fifty thousand couplets, and where all of this comes from.
The Shahnameh is a single poem about fifty thousand couplets long, written by Ferdowsi over roughly thirty years and finished around 1010. It runs from the first king of the world to the fall of the last Persian one, and it is the reason the stories in it are still around, along with a good deal of the language they are written in.
It is not a war book with a plot bolted on. What it keeps coming back to is what a bad decision costs, usually to somebody who had no part in making it. Kings in the Shahnameh are as often the problem as the fix, and the poem says so out loud.
Half of it is legend and half is closer to history, and the join is not where a modern reader expects. Rostam's seven stages into Mazandaran sit well inside the legendary half. That is exactly why they can be the shape of a game.
In the game
Everything in the game is taken from it: the road, the order of the stages, the names on the pieces. None of the mythology here is made up.