I like fantasy, and there's "believable fantasy" and "unbelievable fantasy". If you start saying the world has some unusual property X and then show the consequ

I like fantasy, and there's "believable fantasy" and "unbelievable fantasy". If you start saying the world has some unusual property X and then show the consequences of that, that's believable - maybe in the future there will be some technology, or physics, or whatever that show how a world with X could actually come to be, but it's the starting assumption of the work. Dungeons and Dragons has magic, but it has a rule system, with some form of thermodynamics-y like stuff, internal consistency. Dune starts with some rules and largely doesn't violate them (and if it does, that makes it less kinda good).