terrain.center_bumpIsland shape
What it does
Forces the middle of the map to be land no matter what the ocean-carving noise wants it's why the centre of Rust maps is almost always solid ground. A bigger bump also lets hills and mountains grow taller inland.
What you seeRaise it and the map fuses into one solid continent with a hillier, more mountainous interior; drop it to 0 and the middle can fragment into islands and inland water.
Gotcha
It isn't a literal hill in the middle — it just guarantees the middle is land. Setting border_falloff to 0 switches the bump off entirely.
See it on a real map
Reference seed 12345, size 4500. “Try live” opens the generator with the value applied.
default 1.0
0 — fragmented, random core try live →
2 — solid continent, tall interior try live →
-1 — flooded interior, inland seas try live →