Worldbuilding can be hard. If you're creating a story that isn't already set on Earth at some point in history, you'll have to come up with a lot of different things on your own. And not just the names of places and what transpired, or what kind of culture each different people has, but also the more subtle parts of a setting that include tone and visual aesthetics.
That's why a lot of fictional worlds tend to cleave to a particular setting aesthetic, an amalgamation of different ideas that can loosely be thought of as setting genres. These are not hard and fast rules, as some different aesthetics may blend into one another, but they tend to stick primarily to one type of aesthetic. These terms can be applied across literature, movies, games, etc.
- High Fantasy - The default type of setting for most fantasy settings. Magic is commonplace, as is anything we normally associate with fairy tales and mythology. High Fantasy tends to be a bit more upbeat, as many civilizations tend to exist quite comfortably (apart from the odd dragon or zombie attack). Big focus on cosmological conflicts, namely Good vs. Evil.
- Low Fantasy - The dark and gritty counterpart to High Fantasy. Not necessarily Grimdark, although life does tend to be harsher. The biggest exemplar of Low Fantasy is Conan the Barbarian; magic is uncommon but very powerful, political strife is more commonplace, and violence is the norm.
- Heroic Fantasy - Intermediary point between High & Low Fantasy; High Fantasy backdrops and upbeat take on the world, but Low Fantasy-esque focus on Your Dudes. Grittier and more grimdark examples do exist - Warhammer Fantasy Battles and Roleplay are technically Heroic Fantasy.
- Sword & Sorcery - The pulp magazine version of Heroic Fantasy, traditionally leaning more towards the Low end of the scale and incorporating some level of Science Fantasy elements in it.
- Dungeonpunk - Heroic Fantasy with Punk stylings and magitek, usually of the "industrialized magic" variety.
- Gaslamp Fantasy - Victorian-themed (or at least painted) world with magic in it, the fantasy analogue to steampunk.
- Dark Fantasy - Grimdark or Horror take on your standard fantasy world.
Examples: Warhammer Fantasy
- Modern Fantasy - An alternate take on Urban Fantasy, where you have a fantasy world that's developed magic and/or technology until it's reached a semblance of the modern world. Or at least a historical/futuristic analogue to our world.
- Weird Western - Either a Western version of Urban Fantasy, or a fantasy world that has Western themes.
- Cyberpunk - The original of the "punk" genres. If you've ever seen The Matrix, that's pretty much Cyberpunk in a nutshell, although Blade Runner is probably a more classic example. Dystopian urban environments and highly advanced technology is commonplace, as are dark, brooding heroes wearing black trench coats and megacorporations which have more power than any government. High tech, low life.
Examples: The Matrix, Cyberpunk 2020, Blade Runner, Shadowrun
- Steampunk - One of the first derivatives of Cyberpunk, at least in name only. In actuality, the aesthetic draws quite a bit from the works of Jules Verne, which takes place in Victorian times and features more advanced versions of the steam-powered technology of the day.
Examples: 20,000 Leagues Under the Sea, Warmachine
- Dieselpunk - A darker and grittier version of Steampunk set between the World Wars. Tyranny and warfare is commonplace, as are machines capable of deadly efficiency. Typically features nazis in one way or another, sometimes as the winning side of WW2.
Examples: Command and Conquer: Red Alert, Bioshock
- Atompunk - The name applied to anything inspired by the science fiction of the 1950s and early 1960s. Space exploration is the norm, and technology is mostly based on what was slowly beginning to emerge at the time that we would now take for granted (such as video chat, portable phones, robots capable of walking) or else has proven to be wildly impractical if not impossible (Jetpacks, flying cars, ray guns, robots capable of independent thought).
Examples: Buck Rogers, Fallout
- Clockpunk - Steampunk's older brother, borrowing its aesthetics from the Renaissance and Baroque eras.
- Space Opera - The grand-daddy of Sci-Fi, Space Opera features a multitude of worlds, races and technology that play loose and fast with the science part for the sake of a wide, bright adventure in SPAAAAACE! Space Operas are filled with larger-than-life characters, space-nations loosely based on different earth societies and great, galaxy-saving adventures, though it can easily be zoomed in to a planet- or even a party-focused story if needed.
- Science Fantasy - Science Fiction and Fantasy gleefully mashed up, so you can wind up with elves with laser pistols, sword-wielding robots, and dragons flying between the stars.
- Lovecraftian: A type of horror setting that is either directly based on or inspired by the works of H.P. Lovecraft, especially the Cthulhu Mythos. The main concepts revolve around monsters and deities whose mere existence is so horrible that knowledge or direct perception of them drives people insane, and feature copious amounts of existential dread.
- Star Western - Western elements in a science fiction or Space Opera setting.
Examples: Star Trek
- Magitek - Magic has either replaced technology or been assimilated into it.
- Urban Fantasy - Our world, but with magic and/or science fiction added to it. Considered by many the "easiest" sort of setting to get into by casuals & normies. Can be further seasoned with many other aesthetics.
- Weird Wars - Urban Fantasy meets war stories, when one of our world's wars gets magical and/or super-science added to it.
- Isekai - Your dudes come from the real world, but have been sent to a fantasy (or, more rarely, sci-fi) land.
- Post-Apocalyptic - The world ended, and now it's time for adventure! Expect rusted metal, moral ambiguity, relatively high-tech, mutants and lots, lots of sand.