A defining characteristic of many Settlers IV maps is the scarcity of surface stone. Unlike wood, which is renewable via foresters, stone is finite. Maps are often designed with loose stone piles placed at a distance from the starting headquarters. This design choice forces a specific strategic opening: players must rapidly expand their borders to secure stone quarries before they are boxed in by rivals. Without stone, players cannot build military structures (towers and castles), effectively rendering them defenseless.
Official Ubisoft map editors are long gone, but the community is still active.
Terraforming the Colony: An Exploration of Design and Strategy in The Settlers IV Maps