Within any fiction there are rules that the universe follows, and you 'immerse' yourself in them by wilfully suspending your disbelief. An example is Wile-e-Coyote. He runs off a cliff and gravity does not happen until he notices. Then he falls.
Realistic, nope. Immersion breaking, nope because that's the rules of his and road-runner's universe.
Harry Potter is a Wizard, realistic, nope, immersive, yes as his magic world has its own rules he and the cast have to follow.
You surrender to this with every book/film/game you watch. Sometimes very deeply, sometimes not.
Whenever the universe rules shift, you feel cheated and step out. For example, a character breaking the fourth wall and talking at you reminds you it's a film. A character wearing a different tie every time a conversation cuts back to him reminds you it's a film. Indiana Jones surviving a nuclear explosion in a fridge reminds you it's a flim. Film makers try to avoid it. The spooky Alien is not spooky if it's obviously a glove puppet, and you see the operator.
When the universe rules change it causes problems, quite significant ones in some cases, as suddenly vast tracts of it may make no sense. An example would be the eagles in Lord of the Rings, the film never adequately explained why they couldn't just fly in, dump the ring, get out. Now you can carry it off by hoping nobody notices, or you can't. If, instead of the Eagles Frodo suddenly said 'oh yeah, I forgot, we can both fly Sam, let's fly out of here' and Superman like they flew back to Minas Tirith you'd be thinking 'what just happened?' You've left the film and, dare I say it, your immersion is broken. You feel cheated. it's a cop-out. Almost as much as 'and she woke up and it was all just a dream'.
Some works do this. Sometimes for comedy effect, sometimes for a more avant-garde reason, and sometimes it just 'fits'. The Monty Python universe is silly, it follows no rules really, but you accept the lack of rules as that's the rules. Sometimes (The Big Short does this) a character breaks the fourth wall, in that case he's the narrator and it feels a bit more natural as he's telling you the story. But that's fine, it's the premise of the film.
I'm rambling, but the point is to make something engaging it needs its own ruleset applied consistently, or if there is to be change there needs to be a massive reason for it, and it needs to be well thought out to avoid being jarring.
This. 'Space magic' or the equivalent is a necessary part of many games. But it needs to be internally consistent. Such consistency is one of the things that distinguishes the best games from the merely average.