The world my striped yeen demon Khayoz and his twin Haku were born in.

it has seven moons and purple lightning hits the ground every now and then, making the ground crack and split.
There's no sun.
Either the moons shine or it's completely void of light.

In the middle of the world is a crystal that is the core of that world. Would it ever get destroyed, then the world would fall apart and be nothing but drifting pieces in the void around it. That crystal is so powerful that it's extremely hard to even just be close to it.

The closer a being can get to the crystal, the more powerful they are. It's said that whoever can touch the crystal gets to rule that world as it's king. Maybe there is a king already, Maybe it's just a legend. Maybe the crystal is home to the king. Who knows.
When all moons go black, all demonic powers go crazy.

They all instinctively know that now is the time to get close to the crystal, so they fight over it, constantly. They're drawn to it's power and when the light comes back, the being closest to the crystal gets the chance to fight their king and take their place, as they try to withstand the crystals force and touch it.
It's a very chaotic dark fantasy world.

it's a flat world, you can literally fall off of it and land on the first plane of the nine hells of the world if you do. The nine hells are called Niedertief-ebenen (netherdeep-planes) There's also 7 planes of 'heaven' above it, called Schimmerhoch-ebenen (shimmerhigh planes).

Khayoz and Haku were born in Donnernacht (thundernight), the part of the world Immernichts where the dominant force is lightning.
The other parts of the world are:
-Schattenfrost (shadowfrost, the ice part of the world)
-Aschegrimm (ashengrim, fire)
-Abyssfall (water)
-Silbersturm (silverstorm, air)
-Wüstenriss (desertrift, earth)
-Nimmerlicht (neverlight, light)
-Immerdunkel (everdark, darkness)
And last but not least there's Nirgendweg (nowhereway, the void in between the planes and around the world).

The beings in this world don't get 'born', they just form from the energy around them (like Khayoz and Haku, who were originally nothing but a spark of lightning and fire respectively, that gained a conciousness by absorbing some of the power around them).
Beings can have any shape, they don't even need to have a set physical form at all. They don't have genders at first, they can take any shape they want. As they get older, they usually settle for one kind of shape, but are still able to adapt or change depending on their surroundings.

There's also these storms that occour if the seven moons are all full moons at the same time. These storms create something like portals that get you to random places. It's rare, but beings can even end up in other worlds or other planes of existence like this. That's how Khayoz and Haku got to other worlds. These kinds of storms don't happen very often.

the moons phases seem to shift in different time frames to one another, but the outer moons mirror their counterparts on the other side of the middle moon.

Maybe the moons are different worlds too, which each have their own crystals and thus they create their own light. And the stars are small crystal fragments that have the potential to one day become their own.