This datapack repackaged as a Mod depends on Ecological Expansion (for the world gen used by the dimensions added) and creates a custom config for Forgiving World (for travelling through the layers.)
The world is populated mostly by floating lands, add biospheric layers with their own floating land generation, as dimenisons you can travel by flying above or dropping below.
Vanilla portals are disabled- To travel thru dimensions you need to go to the ceiling or bottom of the dimension to go to the one above/below respectively, here's a map of the dimensions and how they're stacked:
The End
Void
Exosphere
Thermosphere
Mesosophere/(overworld)
Stratosphere
Troposphere
Lithosphere
Athenosphere
The Nether
Project members
Yakiko