terrain.noise_base_shapeIsland shape

The game starts with a map completely full of land, then uses this command to carve the ocean into it — so this one setting decides your island's whole outline, and every other command only decorates the land it leaves behind. freq sets how big or small the carved bays are, amp is how deep the carving bites, and offset tips the balance (positive = more ocean, negative = more land).

Raise amp and the island shrinks and shatters into fjords and scattered islands; drop it toward 0 and the coast smooths out until the map is one giant plate. Higher freq = lots of small bays and islets instead of a few huge lobes.