Magic Knight Rayearth has an interesting subversion. Cephiro itself is certainly Medieval European Fantasy. But the three Magic Knights are summoned from Japan. And Autozam represents the United States of America, Chizeta represents India, and Fahren represents China.
Record of Lodoss War (Based directly on the creator's Tabletop Games campaign. They started out playing Dungeons & Dragons but later switched to the Japanese system Sword World RPG and, after that, a game system of their own invention.)
Even though the world they are set in bears only minute resemblance to actual Medieval Europe; for starters, Feudal governments seem almost nonexistent.
Actually, Middle-Earth is distinctively medieval, but is based on early medieval concepts, not the more popular 'high medieval' setting.
It feels more like Dark Ages almost. Especially when one looks at the artwork of Alan Lee, there is a distinctly ancient look about certain elements, like the late roman inspired Gondor.
Willaim Morris's The Well at the End of the World and its other related novels, which helped inspire the above.
The Deryni works of Katherine Kurtz feature feudal governance and a Christian Church to rival the secular government.
Being based on the setting that gave birth to RPGs, more or less any book universe based off of Dungeons & Dragons. Especially Dragonlance.
Averted by the Earthsea Trilogy: the people are various shades of brown (except for the barbarians, who are white), and the society seems more ancient than medieval.
Ranger's Apprentice is a young adult/children's series with this setting. Occasionally the stories move beyond "Europe", however.
Although George R. R. Martin's A Song of Ice and Fire is set in the fictional continent Westeros, there are a lot of references to tournaments, jousting, greatswords, lords, and bannermen, ale, and people calling each other "Ser..."
George R. R. Martin has pretty much admitted this - the Wall is, unsurprisingly based on Hadrian's Wall, the Red Wedding is based on the Black Dinner, where the chiefs of Clan Douglas were murdered in Edinburgh Castle.
Osten Ard, the setting of Memory, Sorrow, and Thorn, strongly resembles Medieval Europe in terms of society (though not so much geography) with a number of direct Fantasy Counterpart Cultures and an obvious Catholic Church-analogue.
D&D actually subverts this trope big time. Only Greyhawk and Faerūn truly qualify. Maztica is Mayincatec, Kara-Tur is Far East, Rashemen/Thay is Darkest Africa, Zakhara is Qurac of Arabian Nights variety, Athas is based on Ancient Mesopotamia/Egypt , Ravenloft is Anachronism Stew with strong hints of 19th century, Dragonlance, despite its chivalric orders is vaguely pre-medieval and don't even get me started on Planescape multiverse...
Justified in GURPS Fantasy with the world of Yrth, where a massive magical backfire several centuries before the current date transported in large numbers of humans from medieval Europe, who then did their best to build themselves a new home that looked and worked more or less like what they came from. Simultaneously double subverted by the nation of Sahud — first, it was populated with medieval Asians, and second, they were mostly peasants from four or five different cultures, who tried to do the same as the Europeans but ended up with a society that looked less like any actual Asian nation of the period and more like The Mikado on acid, as written by Monty Python.
Most countries in 7th Sea, although the ruins of the ancient Syrneth civilization mix things up a bit.
Again, only Ussura is truly medieval. Other countries are well into mid-17th century Renaissance, with Age of Exploration and Thirty Years War playing key roles in the world development.
Ars Magica even calls its setting 'Mythic Europe' and is set in historically correct settings with many folklore and religious fantasy thrown in for the good measure. In a nutshell, it is the actual medieval Europe with all fantastic beliefs made true.
King Arthur's Pendragon, as the name suggests, is based on Mallory's version of Arthurian England, mixing high-medieval setting with magic and Celtic paganism.
Das Schwarze Auge, has Aventurien, a rough equivalent of Europe with Mittelreich modeled after the Holy German Empire. Other countries and lands also fit the role of Fantasy Counterpart Culture.
Warhammer Fantasy Role Play has Old World that is late medieval/early Renaissance although Kislev and Bretonnia (at least from 2nd edition onwards) play this trope straight. High Elves and Dwarves also fit the feudal mindset pretty well.
Chrono Trigger subverts this by starting out with two time periods that fit this trope, then taking you to a high tech future.
1000 AD seems to be pretty schizoid, though, seeing as how they have refrigerators, stoves, apparently large-scale power plants that would be necessary to operate both, guns, mechanized warfare, and steam power (the ferry,) but there are no cars or paved roads, and Guardia's standing army has no firearms. On the other hand, Guardia is the sole world power in 1000 AD, so it's not like they need firearms.
The first five Final Fantasy games go in and out of this. The seventh, eighth, and thirteenth games are very much not examples, but most of the rest have some degree of this. The tenth has anti-technology, but that turns out to be the Big Bad's plan.
Subverted in Breath of Fire III (To some extent) and especially in Breath of Fire V: Dragon Quarter, which, while not necessarily in the same "Canon" as the others, is set inside an underground sci-fi world made to escape the pollution on the surface. It's assumed by fans to take place long after Breath of Fire III.
Most of the Star Ocean games attempt to avert this by setting up a sci-fi universe, but fall right back into it by leaving you stuck on an 'undeveloped world' (which are mainly Medieval European Fantasy worlds) for most of the game.
The Warcraft series, at least as far as the human kingdoms are concerned. The third game and the MMORPG add a slew of other settings, such as the vaguely Asian nightelves, the Native American-ish Tauren, Caribbean Trolls, the Steam Punk gnomes (and goblins), the Magitek-using draenei, vaguely Persian-ish Blood Elves, and the nordic vyrkul.
Not all the human kingdoms are medieval either, as Gilneas seems to be based on 19th-century London.
The original Diablo has this in full force. Act One of the sequal takes place in the same medival region, but quickly departs it in favor of Qurac, Mayincatec, Hell, and the a scary snowy place in that order.
Guild Wars nails this trope in all other aspects but subverts it when it comes to geography: The tutorial level of Prophecies (pre searing) looks like the game would be something like this, with medieval castles, green Ghibli Hills and otherwise European geography. Then the Charr summon their Earth-Shattering Kaboom. Ascalon ends up as a broken wasteland and every other locations tries to avoid this trope. The rest of Tyria is (in order) Death Mountain, a Beach Episode, Jungle Japes, Shifting Sand Land, Slippy Slidey Ice World and Lethal Lava Land / Mordor. The continent Cantha in contrast is the Far East while Elona has heavy African influences.
Mount & Blade, which tries to keep as close to a realistic medieval setting as is physically possible, has this trope as its entire point.
Dragon Age games and books take place in a Fantasy Counterpart Culture setting, where most countries/cultures having a prototype in our history. The nations of Ferelden and Orlais are based on Medieval England and France, respectively, right down to the accents. Antiva, though never shown, is described like Rennaissance Italy, although Antivans have a Spanish accent for some reason. Other parallels are less Clear. Interestingly, Dragon Age: Origins does not include any horses or mounted warriors, reducing the image of a knight a little. The novels, on the other hand, have them in spades. The Orlesians, for example, fight mostly using their heavy cavalry troops known as the chevaliers (French for "knights"), while the Fereldans prefer infantry, with a mix of magic and war dogs thrown in.
Phantasy Star III has a variant: it turns out that the entire medieval-style world the game takes place in is in reality an Arc-like spaceship that was fleeing the destruction of a very technologically advanced planet, and all the inhabitants are descendants of the ship's original population. After about 1,000 years and a lot of conflict, they lost their ancestors' technological advancements as well as the knowledge about the real nature of their world.
