Demons

By now most of you who read this blog know that we use the World of Fletnern (available at this link for FREE!). On Fletnern, there are several races that are not considered to be “native”. Yep - They are from other planets. Planets, dimensions, realities, does it matter?
Eons ago I remember reading a series of novels (that were turned into comics if I recall correctly) where “demon” was short for “dimensional traveler”, and “demons” were simply people from other dimensions and not actually evil creatures from hell. I kind of like that. Sure I call some of the minions of the less nice gods “demons”, but those are different. When you need something truly creepy, you can just have someone summon something from another dimension. It doesn’t have to be a magical creature, just something so alien (sorry but it is the best word) that it seems to be perfectly evil.
Why? Well magical creatures are magical. They likely don’t have to eat, they are more likely more esoteric, and well, magical. I like having things like aliens rats - sort of a cross between an armadillo and a retriever. I had a slime dog that looked like a glowing dog, but its bones were able to smush. It was a real dog, but it could go through tiny cracks under doors and such. These are creepy creatures, but they’re flesh and blood. Sometimes, you don’t want the glowing dog to be some astral/ethereal ghost creature with a death gaze, but instead a really nasty predator that eats its prey and leaves a trail.
How do you bring them in? Here’s an easy way. Think of a double helix - you know, like DNA. Now have each strand spin in the opposite direction. Well the two strands will bump into each other, at different points as they go. That’s what the spiral stairway is like. Not exactly (I can’t have it too easy to figure out), but sort of like that. That means that every once in a while the worlds arranged on the spiral staircase will bump into each other and the “shells” around the two worlds will break down, allowing people to travel from one to the other. Better hurry or you’ll get caught there and won’t be able to get back until the worlds bump again. Might be a couple years or 500. (The spiral stair is NOT physical; it is sort of a ley lines kind of thing where the magical aspects of the worlds bump. That makes it even easier to keep the players from figuring it out.)
How’s it work? Well, random critters might wander across and now you have some truly monstrous creatures, but very rare. (Bigfoot anyone?) You can have nomads wander across and not be able to get back, setting up weird race villages hidden in the ______. You can have invaders or explorers come across with full knowledge of what the stair will do. Maybe they’re raiders looking to loot and get back before the doors close. Lots of possibilities! Single adventures or whole campaigns, use it as you like! Of course, they could use starships, but that seems to take the fun out of it.