Midgard Ringworld One being invaded by alien-conquered Asgard pushing lesser wars into outer Midgard Ringworlds.
Bifrost connected Realms. Using it allowed transfer from the Ringworld of one Realm to the same numbered Ringworld of another Realm. The invasion of Asgard shattered the Bifrost and created dungeons, gates, and rifts.
Travel to neighboring Ringworlds of the same Realm means going to the border and passing through the edge mountains to the land or water side. It can also be done by flying or gliding depending on the level of technology allowed. Vanaheim’s elves are particularly good at gliding across. The dwarves on the other hand shy away from flying and prefer to set up a structured system to aid passage if the Ringworld allows it. If not, they are known to use animals to assist.
Travel to the water side from land side can be done by climbing over the edge mountains and into the forever falls of the ocean side before the bordering ringworld swings in. Relatively easier is to go through a whirlpool in the Ringworld’s middle lake. That shoots out onto an island chain in the middle on the other side.
Controlled travel between realms is now restricted to Ringworld Ones to Ringworld Ones and only ones directly to either side or up or down.
So Vanaheim and ‘s ringworld ones are being invaded by the Aliens that conquered Asgard. They are doing this all at the same time. Midgard included. Alfheim and dwarf land are safe.
The realms:
Vanaheim, Asgard, Jotunheim, Alfheim, Midgard, Nidavellir, Niflheim, Helheim, and Muspelheim.
The Three Heavens–Vanaheim, Asgard, Jotunheim, The Realms of Leaves. Home of vanir, aesir, and jotun. The Highborn.
The Three Folklands–Alfheim, Midgard, Nidavellir, The Realms of Branches. Home of elf, human, and dwarf folk. The Folk.
The Three Hells–Niflheim, Helheim, and Muspelheim, The Realms of Roots. Home of frostkin, sinborn, and ashkin. The Demons.
The Trunk, The Three Central Ringworlds of the Three Central Realms. More specifically, the World Tree’s actual Trunk.
The World Tree’s actual dimensions: 32,400 miles from root tip to leaf tip in height and width. This is reached by multiplying a central Ringworld’s diameter of 1,200 by nine to represent all nine Ringworlds that every Realm has and then multiplying this total Realm diameter of 10,800 by three to represent the aligned Realms vertically or horizontally. Minus the Root Realms, the Tree is 21,600 miles tall. Its trunk is 420 miles in diameter at the border between Midgard and Helheim and 345 miles in diameter at the central point and cultural ground level of Midgard. 270 miles at border between Midgard and Asgard. 195 miles at ground level of Asgard.
A spiral goes up and down the trunk and into the Roots and Leaves. This allows travel only from Central Ringworld to Central Ringworld of Trunk Realms.
The Heart, The Central Ringworld of Midgard. More specifically, the base of the World Tree’s actual trunk.
The broken Bifrost:
Creates dungeons, gates, and rifts.
