Want a survival challenge?
Try the canyon world!
If your lucky, you will spawn at Y: 230-256, up at the top of the world. If your unlucky, in a lava ocean at Y: 70.
This world is made of 256 block tall walls, stretching up to the building limit, and lava oceans and narrow width land, surrounded by canyon walls at Y:60-90.
Ores are modified slightly, like iron is more common