[quote=@Fetzen]
Is interplanetary travel a thing between the different populations or has it been such in the past, given there are ruins strewn around half the system?

If the answer is yes: Was/is it implemented by magic, rocket science or even some weird, ancient, alien-looking devices nobody has the faintest clue about but could use anyway? Or neither of these three things? 
[/quote]

Interplanetary travel was possible and used around 8,000 years ago, some scholars believe. There were eldtrich gateways made by unknown beings among the worlds. Some believe it was the Luminar themselves, and others think the eponymous 'builders' created them. They were either destroyed or they lost their power many thousands of years ago now, save for perhaps one or two hidden from the world at large.

[quote=@Lemons]
You mentioned addiction to magic. Explain more, cause that's cool.
[/quote]
Thanks! 
Well magic in my world is a very contentious subject, and the world's religions don't really know what to make of it. It is the very stuff of creation and so in a sense, it is holy. However, magic is often too powerful for mortals to handle and the great prophet did warn about extensive usage of said power. When human bodies, or particularly magical beings like elves, draw in magic, it becomes a part of their form. Much like if someone was used to a lot of sugar in their diet so it was in their blood stream constantly, and suddenly quit cold turkey for a month. Except far far worse. Our very bodies reside in creation and are fueled by it, and so when a mage draws in large quantities of the magic around him, even if it is filtered in through a source such as the realm of shadow, they becomes drunk on the power and the 'nervous system of their soul' becomes reliant on it, so to speak.