Science Fantasy
Science Fantasy is one of the harder Setting Aesthetics to describe. Abstracted into one single sentence, it is a setting including elements from both traditional fantasy and science-fiction. It can take many forms, for science fantasy spans the whole gamut between "Hard Science-Fiction, but something like psionics/magics/... that cannot be explained by science exists" to "Fantasy, but where advanced technology do exist as is mistaken for magic".
Science fantasy dates all the way back to the origins of fantasy as a whole. See, despite modern "purist wars", science fiction and fantasy weren't considered really distinct from each other in the early days. As a result, you had lots of things like magical aliens, barbarians wielding laser pistols as they rode across post-apocalyptic worlds, time traveling sorcerers, and so forth. (The most telling example is Conan the Barbarian, archetypal Fantasy hero, encountering space-faring travellers in his adventures.) It's a very fertile aesthetic, and is not going to be going anywhere any time soon.
Examples of Science Fantasy on /tg/ include:
Numenera: A world presented in classic fantasy style... except it's actually set on an Earth billions of years into the future; all of the "magic items" are actually hyperscience devices whose underlying principles have been forgotten, spellcasters are either using psionics or hypertech gizmos, and the various non-humans and monsters are aliens from other worlds/dimensions, genetically engineered lifeforms, or robots.
Warhammer 40,000: Literally beginning its existence as "Warhammer Fantasy IN SPACE!", 40K is a classic example of the "tech first, fantasy second" aproach to Science Fantasy. The Space Marines are techno-knights cum paladins, the Eldar are spacefaring elves, Dark Eldar tap into all sorts of "nasty faerie boogeyman" archetypes, psionics is essentially magic with sci-fi trappings, the orks are literally just orcs with guns and spaceships...
Expedition to the Barrier Peaks: This Advanced Dungeons & Dragons adventure module revolves around a band of Greyhawk adventurers exploring the ruins of a long-crashed alien spaceship.
Blackmoor: Is a Dungeons & Dragons setting in a world full of advanced science, and it's canonically the pre-apocalyptic past of Mystara. It's also the setting for the adventure modules "Temple of the Frog" and "City of the Gods".
Torg: Original in the sence it allowed multiple "realities" to co-exist (and duke it out) on Earth, so your average party could very well consist of a clusterfuck of a cyborg Hulk, a prehistoric era shaman with his stone-tipped spear summoning a dinosaur to ride in battle, a suave Indiana Jones-esque adventurer and a ninja using both supernatural ninja powers and a machinegun.
Feng Shui: Put it like this; this is a world where psionic monkeys and cyborg techno-barbarians coexist alongside shapeshifting animals, ninjas and sorcerers.
DragonMech: A Dungeons & Dragons setting where the collapse of the moon and resultant cataclysm has prompted the various races to emigrate into city-sized magic-powered mecha.
Dragonstar: A Dungeons & Dragons setting where magic and science coexist, allowing for an interstellar empire run by dragons where cyborg wizards duke it out with laser-packing orcs.
RIFTS: Just... where do we start with RIFTS? To quote our frenemies on TVtropes: The tabletop RPG Rifts is set a few centuries after the high tech world of tomorrow is utterly trashed by the return of magic. Human supremacist armies of cyborgs, chemically-enhanced supersoldiers and Humongous Mecha traipse across the landscape. Atlantis has risen. Sorcerers summon demons and raise the dead. Rifts in spacetime spew out critters from other dimensions more or less at random. Elves and dragons and goblins (oh my) roam the wilderness. Killer cyborgs from another dimension want to kill all humanoid life on Earth. Gods battle Alien invaders. Vampires openly run entire cities. And that's just the tip of the iceberg.
Shadowrun: A world where The Magic Comes Back meets cyberpunk, so you've got dragons running megacorporations, elves with laser pistols, dwarves building killer robots and cyborg orcs & trolls all duking it out on the mean streets.
Pathfinder: Shamelessly using this trope, Pathfinder has everything from a "crashed alien spaceship in a land of barbarians" region on the planet itself to sourcebooks detailing the other worlds in the solar system, so you can involve interplanetary travel as much as you like. Its successor/spin-off Starfinder is basically Pathfinder set 1000 years later, so everyone lives in space after Golarion vanished.
Spelljammer: A Dungeons & Dragons campaign setting that revolves around using magical ships to fly between "crystal spheres" (fantasy solar systems) by way of an alternate dimension called Wild Space.
Draenei: A race from World of Warcraft who originated on an alien planet, were rescued from demonic invaders by angel-like beings made of magical energy, and traveled to Azeroth in gargantuan fortresses magically propelled between worlds.
Escaflowne: An isekai anime in which fantasy races conduct war centered around the use of Guymelefs; knight-like giant clockwork mecha powered by the crystalline hearts of dragons.