First, you'll have to forgive me for getting anything wrong - I have pretty much no knowledge about the subject in the title.

I've recently started up a Numenera game for my friends and have started them on a canned adventure, but I was hoping to eventually explore the idea of them running into a complex/ruin that exists in multiple spatial dimensions. Kind of Fez-inspired, they would need to either change their environment or shift their perspective in order to advance through it. Problem is that I don't really have a grasp of the concept to represent it accurately and I'd rather not just shoe-horn it together.

My musings about this have also given rise to the idea of creatures that span extra spatial dimensions, who's presence in the world of 3D perceiving creatures would only be a fraction of their true form. Imagine a 'Slenderman' that is essentially just a limb for something much larger (and maybe insanity-inducing) that no one else can truly see. Could have them chasing it into the 'dungeon' for a final confrontation.

Has anyone else given much thought to this sort of thing? Does anyone have any guidelines or ideas for exploring that sort of quasi-reality?