"Magic takes over the world"– has this been done?

I don’t mean a scenario where science and physics stops working and is replaced by magic. I mean sort of like if Voldemort and his followers had won the Wizarding World’s civil war and then gone on to enslave the Muggles. Or like alien invaders conquer the world only it’s magic users conquer the world. Now some number of years later the world is ruled by an elite aristocracy of the magical, while the masses of subjugated normals struggle to get by under the capricious and often sadistic whims of their new masters. A subtrope of The Unmasqued World.

Hmm…

I can only tell you that Mistborn begins with the evil villain(think Voldemort or Sauron) has already won and the world is covered in ash.

However, the rest is not like you described. It ends up being about a scrappy group of magic users trying to defeat the Lord Ruler(bad guy).

There’s Weber’s Hell Gate about a war between a universe of high tech and one of magic, and Gaiman’s “A Study in Emerald” which takes place several centuries after Lovecraftisn monsters have taken over the world

The Laundry Files might sort of work. It is set in “our” world, and at the start of the series the main characters are fighting to keep magic from invading the world. As the series progresses magic does invade the world, and various Eldritch horrors take over a bunch of governments.

Problem is that the world of the Laundry Files diverged from our world sometime in the mid-2000s (maybe?), and the events in our world became too ridiculous and unbelievable, making the Black Pharaoh seem like a perfectly plausible choice for Prime Minister.

If it hasn’t already been done, I had in mind to maybe write a story where some years after the takeover a homicide detective gets summarily pressed into solving a high wizard’s murder; a task complicated by the fact that where magic is concerned almost nothing is intrinsically impossible.

Sound similar to The Librarians and the new version. They are always fighting to keep magic from taking over.

Ilona Andrew’s Magic Bites has that premise in its world-building if I remember correctly.

I played the tabletop RPG based on it. It’s very Call of Cthulhu-ish. I played a guy who did magic using a computer that cast the spells. Very interesting world.

Related to such, there’s the whole TORG TT-RPG, where multiple different “worlds” invades our world, each with unique laws which take dominance over areas they control, high fantasy, low-tech/spiritual, two-fisted pulp, cyberpunk, and Victorian Horror.

Not to mention a metric ton of various Isekai novels with similar premise.

The Shadowrun RPG fits the bill. It’s cyberpunk, with elves and trolls, where magic suddenly returned to the world sometime in the late 20th century, but it didn’t displace technology, it supplements it. It’s not exactly a magic dictatorship, but a corporate dystopia where the corporations are run by dragons and vampires.

Piers Anthony’s “Apprentice Adept” series has the sci-fi world of Proton merge with the fantasy world of Phaze at one point.

Similarly..

The premise of the roleplaying game GURPS Technomancer ------ the detonation of the first atomic bomb by the United States triggered a transformation of reality. The mushroom cloud became a permanent magical tornado emitting bolts of red lightning. The resulting wave of magical energy and fallout also modified the genes of countless new-born children. This created both magically apt individuals as well as chimeras — people with some animal traits.

And of course, there’s also Rifts.

The less said of Rifts, the better

Are you kidding? Having a party made up of a baby dragon, a Juicer, a Cyber Knight, a Full Conversion Borg and the poor bastard playing a Rogue Scholar was a lot of fun.

Pinnacle has been converting Rifts to their Savage Worlds ruleset for a few years now. It really fixes the major problem with the game, which was the entire rule set.

Sounds like a fun premisse, though I wonder how you can solve it if nothing is impossible. There probably are some rules even for magic.

-looks at about 4-5 Rifts sourcebooks on his shelf-

Sadly, yes.

Do you count System Apocalypse stories where suddenly people get stats and classes like they’re in a role playing game?

If so Tao Wong’s System Apocalypse is a good example.

The Wizard of 4th Street series would be an example of a basically peaceful takeover. In the backstory of the setting there was a worldwide economic collapse as energy and other resources ran out. Then Merlin came back, as some myths claim he would in a time of need and taught the world how to tap into magic as a replacement. Technology is still around, just supported by and integrated with magic. So they still have cars, but they fly by magic, and they have power plants but the electricity is generated by magic.

In Roger Zelazny’s Madwand books takeovers by both magic and technology seem to be a thing. Magic apparently displaced technology in the distant past, and there’s an attempted resurgence by its forces in the first book. In the second there’s an attempt to tip the balance in the other direction towards more magic, which would apparently be bad for most existing people including most wizards.

Temporary Agency and Unquenchable Fire by Rachel Pollack are set in a world where magic is real and integrated into the modern world. Interestingly, it’s the crunchy granola kind of laws of attraction and tarot card magic, not magic wands and fireballs magic. Nevertheless, it demonstrably works, and you won’t qualify for health insurance unless you keep your chakras aligned.