Would you consider implementing something like this (as an option) ?
https://forums.civfanatics.com/resources/movement-limit.22229/
It limits the movement of units when starting an 'ancient' game, so it takes a while before you can discover the map. Increasing culture or tech gradually increases the distance from cities where units can explore.
https://forums.civfanatics.com/resources/movement-limit.22229/
It limits the movement of units when starting an 'ancient' game, so it takes a while before you can discover the map. Increasing culture or tech gradually increases the distance from cities where units can explore.