Yggspace

Yggdrasill is the sphere home to the Vikings, almost identical to ancient Norse culture. It's an extremely deadly space if one does not know about the ever-present dangerous Portal Vortices.
At the relative bottom of the sphere is the diskworld Midgard/Jotunheim, a place where the mortals and giants dwell, alongside all manner of beasties and dangers of their own. Even Midgard is mostly cold, although it still experiences a Spring and Summer occasionally. These don't occur very often, and when they do happen they last for years. Think "Game of Thrones" types of seasons, they last for years, and the Winters are always much much longer than Springs, Summers, or Autumns. When the campaign begins, Midgard is in the beginning of Spring after a long decade of Winter. Things are still thawing out and "waking up." Jotunheim however is always frozen over, it doesn't have as much access to warmth as Midgard, as Sol the sun only gets close to that half of the disk. She'll still go across the Jotunheim sky, but is much dimmer when she does. Legends say the giants once tried to kidnap her and make her marry their king, and that's why she isn't as willing to give her warmth to that side.
=== Coming Home ===
A steady course along the rainbow sea of the phlogiston, a dragon-masted longship returns home from a voyage to Verithspace. A dark brooding man with long black hair stands beside the helmsman, right hand clasping the Eagle-headed hilt of his greatsword and directing with his left. He radiates strength and calm, and all his crewmen obey his commands without question. The Void Yarl demands nothing short of total respect and doesn't have to convey this through words. An imposing figure, but also a comforting one for his allies, he is a very level-headed man. Unlike the regiment of berserkers upon the ship he's Captaining. Strength comes in many forms and all are valued by the Vikings, but very few will argue with a man who has 30 ravenous barbarians at his beck and call. This is what we refer to as "tactics," as the political counsel is still a battle of its own. Show your might, walk with a big sword and speak softly.
The imposing man braces his feet as the ship passes through the barrier of Yggdrasill, a thin veil that separates his home from the endless sea of highly-flammable rainbow space. It rocks the ship slightly, and the view is simply breathtaking, but also deadly. If one looks at the scene in its entirety, at what seems to be the bottom of the sphere is a massive disk of mountains, rolling hills, lakes, cities, and villages. The water that surrounds it on all sides constantly falls off the edges in a massive continuous waterfall. This side is Midgard, home of the mortals. The flip side of this diskworld are massive mountains of Ice and Snow, reflective of the beings who reside there, and this bitterly cold side is referred to as Jotunheim.
Raising one's eyes upwards, you can see the endless black curtain of the starscape, studded with many, many swirling luminous lights and black orbs. Those are what present the biggest threat in Yggdrasill, all of those lights and orbs are portals. Portals to planes, portals to spheres, portals to nowhere. Dangerous and random, they blink in and out of existence and have a pull stronger than any whirlpool, a ship gets caught in that pull, there's almost no way to get out, almost.  A somewhat hard to see island floats in the center well above Midgard, surrounded by these extreme celestial bodies. The island is the cosmic center of Yggdrasill, the Well of Urd, home of the Norns and many hundreds of travelers and those who are stranded here due to the violent and random portal eruptions.
The Yarl shifts his gaze to the first "landmark" of the journey home inside his sphere, a massive shipwreck splintered and scattered along space, he watches as a similar Dragon headed mast floats by, exactly the same as his own, only older and scratched to all hell. This is going to be close, they're running a bit late returning home thanks to those pompous Elves, the portal to the Elemental plane of Earth is due to open here at any moment. Some portals are consistent when they appear, within a margin of time. They are never precisely exact, sometimes they're earlier, sometimes they're later than when they appeared last. With a little luck, and Odin's favor, the portal will be late in arrival and they'll be past the danger of the event horizon. Without changing his stony demeanor on his face, the Yarl's hand tightens a bit on the hilt of his sword. His breath hitches in anticipation of what happens next.
A blinding flash washes over the deck as the portal streaks into existence early. A small eye close and silent prayer to the All-Father, thanking him for his test of strength. You do not disrespect the gods and their choices, regardless of how inconvenient the situation may be. Immediately, the Yarl's eyes shoot open and he starts quickly issuing commands. The helmsman is the best of the best, his second wife, she already had a handle of the ship and was already moving it according to the plan. The Yarl looks to his wife, Estrid, and places a hand on her shoulder as she navigates the ship directly into the whirlpool's edge. A trick that one must learn to navigate Yggdrasill's deadly vortices, the current is strong, stronger than anything else anywhere on any plane or sphere, but you can use the current's own energy to escape and launch yourself even further at great velocity. However, this maneuver is a deadly game, one wrong step and your ship will be dragged inside the portal, sometimes splintering the ship if it collides with any debris.
Everyone in position, adjusting the sails as the ship is dragged along at greater and greater speeds, it's positioned so that the Mast is facing the same direction as the pull, his wife already prepared for the jump. The ship, Skidbladnir, whips around the outer edge of the portal, and at the last second, they punch it, full-force ahead. Skidbladnir rockets out of the portal's edge like a meteor and streaks down toward Midgard. His breath releases in a small stream as he gives a small smile in acknowledgement of his wife's skills. They were safe, for now, and more importantly, almost home.
== Factions ==
== Dangers of Yggdrasill ==
=== The Vortices in Open Space ===
The Vortices are absolutely deadly, think Black Hole but at the center is a portal to another place. They are scattered, some are consistent and show up at certain times, other are random and can simply pop into existence. Getting caught in the whirlpool arms of the portal can and will shred ships that don't know how to navigate them. The safest way to use the portals is to go through immediately, directly via the front or back of the portal, so as to avoid the whirlpool arms. It is generally unknown where exactly the portal will empty out to, unless it's been explored and documented. Members of the Cult of Fate are willing to pay hefty rewards to those who are willing to explore undocumented portals and safely return with the recording devices. These rewards can be monetary, magic item or service based, or negotiated by the PCs. 
The Vortices have another inherent danger due to their nature. The Burial Mound, a massive ship graveyard is scattered to the outer rim of Yggdrasill. Pieces of flotsam and shreds of unfortunate ships that got torn asunder via the portals scatter the open space like an asteroid field. Collisions with the debris field are uncommon as it's easily navigated, however some places have more to avoid than others. Debris tends to congregate around consistent portal spots, creating an annoying and sometimes lethal obstacle for ships trying to pass through. If a ship gets caught in a portal's gravity alongside the debris, small pieces of wood suddenly become small extremely fast projectiles that can rip through a ship's hull like a hot knife through butter. When the portals disappear, the projectiles keep moving at the same velocity in whatever direction they happened to be going when the portal went away. It's a hazard for sure, but an overall small chance to get hit with it.
== Religion ==
Asgardian Pantheon
== Demographics ==
A genuine melting pot of all races. The strong survive the Winter. Midgard side: Mostly Human, Jotunheim side: Mostly Giants/Goliaths/Beastial Races
== Celestial Bodies ==