Never Was This Universe

Alternate History provides a method for creating a setting which is almost like our world, but varies in large enough ways that they couldn't plausibly actually be ours.

This trope covers settings which feel like Alternate History in this way, but don't actually have a specified point of divergence: no matter how far back in history you look, their history has always been different from ours in some way (frequently, though not always, because it contains un-Masqueraded fantasy elements). In Spite of a Nail is necessarily in effect, in order to keep the setting approximately similar to the real world--indeed, sometimes the histories of these settings are more different from reality than their presents.

Compare Alien Space Bats; it's nearly always possible to Retcon this sort of world into an alternate history with Alien Space Bats, by adding in a point of divergence that's earlier than any other history you've introduced. Also compare Historical Fantasy. See also Close Enough Timeline and Rubber Band History. Contrast Plausible Deniability.

Anime and Manga

 * Code Geass is like this. While there's a whole alternate history worked out, the show's mythology relies on things like a free-energy supplying mineral called Sakuradite (that powers giant robots) and a society of immortals who give out mental superpowers to people and then pass on their immortality to them, so clearly there's something different going on that isn't just caused by the differing historical events. It could be that whatever is going on is what caused history to be different in the first place.
 * And on top of that, the most common mental superpowers involve some form of memory alteration, so that alternate history is itself unreliable.
 * Wings of Honneamise Royal Space Force takes place in a world that resembles Earth during the beginning of the space age, but with many differences, some more noticable than others.

Comic Books

 * Both The Marvel Universe and the DC Universe are like this. Both have specific differences from ours *from the very moments of their creation* eg. billions of years ago, and include all sorts of strange stuff, not just superheroes. Even if you removed all of these elements, you end up with Earths that have several cities and countries that never existed in our world. Despite this, historical events such as the 9-11 attacks keep happening, obviously to make them feel more 'real.'
 * The "World of Two Moons" in Elf Quest is very much like our world, except that it has two moons. And elves, but they came later and.
 * The League of Extraordinary Gentlemen takes place in a world whose history is based on the fiction of our reality, even in ancient times. For example, The Trojan War is not only historical fact, but Britain was also settled by survivors of the Trojan War. The history of this Earth also includes such things as Cthulhu and the other Elder Gods fighting a celestial war with the divine beings of the Christian theology at some point in prehistory, the Hyperborian Age occured just before conventional history begins, and instead of Elizabeth II ruling England, Henry the Eighth had a half faerie daughter named Glorianna.
 * At first, Watchmen may seem like a case of In Spite of a Nail or Alien Space Bats: the timeline appears to have diverged from ours in 1938 with the emergence of costumed heroes, and more drastically in 1959 with the birth of Dr. Manhattan, who has actual superpowers. However, a close look at the details of the comic hint that the timeline diverged a lot earlier than in 1938. In the world of Watchmen, the famous Heinz slogan is not "57 Varieties", like in our world, but "58 Varieties". Also, apparently The New York Times doesn't exist at all, it's been replaced by the fictional New York Gazette. In our world, both the coining of the "57 Varieties" slogan and the founding of The New York Times took place decades before 1938, so the implication is that there were subtle differences between our timeline and the Watchmen timeline long before the costumed heroes entered the scene. With "58 Varieties", it's theoretically possible that the new slogan simply replaced "57 Varieties" sometime after 1938, but New York Gazette already existed in 1938, as Hollis Mason's autobiography mentions the paper reporting the initial exploits of the first costumed hero, Hooded Justice. There are also other differences between our world and the world of Watchmen — such as — that seem to be unrelated to the costumed heroes or Dr. Manhattan, therefore suggesting that world of Watchmen was never ours to begin with.
 * It could also be a case of the authors not wanting to violate trademarks, or even simply, mistakes.

Literature

 * Terry Pratchett's Nation is an alternative history where the geography is a bit different (including a sunken continent which was also . Also, North America is one state.
 * Lyra's world in His Dark Materials had a definitively different version of the Protestant Reformation than ours, as well as a society of sentient armored bears which has been around for considerably longer than that. Plus, y'know, the whole visible and living souls thing... And much more...
 * Sunshine and Dragonhaven by ~Robin McKinley~ both do this--Sunshine is set in a world with vampires, and Dragonhaven one with marsupial dragons.
 * Naomi Novik's Temeraire series is set in the Napoleonic era in a world where there have always been dragons.
 * Jonathan Strange and Mr. Norrell is set in Regency-era England with the addition of fairies and magic. Its medieval past is considerably different from ours, as northern England was a separate magical country.
 * In Diane Duane's Next Gen novel Dark Mirror, written before the Mirror Universe made its television return, Captain Picard studies his counterpart's library in an attempt to find a divergence point. After finding some truly horrifying variations on Shakespeare and Homer, he considers taking a look at the Bible... and decides it's better left alone. Turns out the universe has been dark from the beginning.
 * Second Sons fulfills the trope, but inverts the normal working of it. Instead of taking place in our world with magic, it exists in a perfectly plausible world that has no magic, no species that don't exist in our world, and no supernatural elements of any sort, but happens to not be ours, as is cemented by the existence of two suns.
 * The Case Of The Toxic Spell Dump by Harry Turtledove takes place in a universe much like ours, except all the science and technology has been replaced with magic; somehow, this hasn't kept the CIA from employing spooks (only now they're real ghosts), and even crosswalks and hermetic seals retain their names despite their origins differing wildly from our world.
 * Another work by Harry Turtledove, A World of Difference, is based on the idea of Mars being replaced by a habitable Earth sized-planet. Earth is however almost identical to our timeline, despite the fact that "Minerva" is the brightest object in the night sky, which you would think would have an effect on mythology and astronomy. The only noticeable difference is quite late - the assassination of Mikhail Gorbachev meant The Great Politics Mess Up was avoided and a US-Soviet confrontation and war scare over Lebanon leads to both sides sending separate manned missions to Minerva in 1990.
 * Turtledove also has a fondness for replicating early American history in bizarre settings, such as one where the Americas were colonized by Homo erectus instead of paleo-Indians and the megafauna survived (A Different Flesh) or another where the entire East Coast detached at some point in the Mesozoic and became an island continent inhabited by flightless birds a la New Zealand (Audubon in Atlantis and sequels).
 * The world of Go Mutants differs from our own in a plethora of ways, ranging from the truly bizarre (the existence of Gojira and other Kaiju, aliens landing on Earth and interrupting a baseball game in 1963) to some things more mundane (Nixon beats Kennedy and is later assassinated by John Glenn), but it's definitely not even close to our universe.
 * The Bartimaeus Trilogy is set on a Present Day Earth much like ours, but different in that functioning magic exists and takes the place of more advanced technologies--and there was also an Atlantis.
 * According to Word of God, though Urth is ostensibly a distant future of our own Earth,, The Book of the New Sun Never Was This Universe.

Live-Action TV

 * The Buffyverse, while seeming like ours until the mid-2000s, diverts wildly in many places. Hitler was trying to build a vampire army. The US Government was trying to build a vampire army at the same time. Demons, vampires and other creatures have existed since the beginning of our universe, which was ruled over by the Old Ones. Mass carnage created by them was a common sight in the past. And a California city doesn't exist, instead being replaced with Sunnydale. Oh, and Cleveland is, in a clear violation of anything physically possible, actually even shittier.
 * The Mirror Universe in Star Trek is said to be of such a nature. In the Star Trek Enterprise episode "In A Mirror Darkly", mirror Phlox says that he's looked through the USS Defiant's database and found consistent differences in history and culture--with the exception of Shakespeare, whose plays were "equally grim in both universes".
 * The TV series Kings apparently does take place on Earth, but the exact location of the fictional countries is never revealed and the precise historical era remains a mystery (though the society and tech ranges from Cold War to Twenty Minutes Into the Future levels). The only clear-cut reference to our world is a throw-away line about Franz Liszt.
 * The Alternate Universe seen in Fringe looks to be this way as there is no set divergence point mentioned, as of yet. But the map of the US clearly shows different borders for states plus most of California is missing, the Zeppelins, Martin Luther King Jr. is on the twenty instead of Andrew Jackson, and their technology is a little more advanced, although a lot of what was shown was created by.
 * The Flash Sideways on Lost was this to the show's main timeline. It was first shown to the viewers following a major cataclysmic event in 1977 which was implied to be the reason for timeline divergence. Later episodes however revealed that small differences between two timelines existed even before that date.
 * The alternate universe Mickey and the Tylers settle in on Doctor Who is implied to be something of this sort; they mention many earlier points in history that are all different, but later ones really aren't any more different than earlier ones.
 * The alternate universe seen the the Third Doctor serial Inferno is similar.

Tabletop Games

 * The world of Deadlands initially appears to have a simple point of divergence on July 3, 1863, when supernatural events start occurring - beginning with the dead at Gettysburg getting up and trying to eat their comrades. It turns out that the supernatural has always been around, but was "locked away" from this dimension sometime during the Middle Ages until Raven brought about his "Reckoning."
 * Castle Falkenstein is set in an alternate Victorian Era with faeries and dragons.
 * Several worlds in the GURPS Infinite Worlds setting, most bizarrely the United States of Lizardia (its history is just the same as ours, except the people are intelligent dinosaurs). Parachronic researchers usually claim these worlds were created in reality quakes, but they can't always prove it.

Video Games

 * Strangereal in the Ace Combat series is an alternate version of our Earth with virtually identical nature and humans and a roughly Present Day tech level, but the continents are completely different (their shape often hints at an amusingly warped and twisted version of our real landmasses). The countries and nations are completely fictional as well, but are all thinly-veiled Fantasy Counterpart Cultures.
 * To some degree, Fallout. Sure, the point of historical divergence can be pinned down to the 1940s, but their laws of physics (especially involving nuclear physics, of course) are different enough that it would mean that the real point of divergence would have to have been sometime during the very formation of the Fallout universe.
 * What Touhou shows of the world outside of Gensokyo seems to put it in this trope. Youkai and magical creatures co-existed for millennia with humans (and some still do), Physical Gods were actively worshiped until disbelief threatened their ability to work miracles, some of the first humans left Earth to form a new society on the moon, and magic was (and to some extent still is) quite common--but the history of the world nevertheless progressed quite similarly to our own.
 * The MMORPG City of Heroes is much like this; even though the history of its Earth follows many of the same events as those in our world, there is no clear point at which they diverge, as events such as the magic-laden wars between Mu and Oranbega take place thousands of years in the past.

Web Comics

 * Girl Genius, probably. It hasn't been confirmed yet, but while it possibly takes place in an early, exaggerated industrial revolution no amount of Fan Wank has had any success nailing down a potential point of divergence (but at least a couple centuries back, given that Rembrandt is implied to have been a spark). And unlike most examples, In Spite of a Nail doesn't appear to be present, the closest being vague allusions to historical characters like Louis XIV ("Storm King" instead of "Sun King") and the aforementioned Rembrandt (although only as "Van Rijn", and he's known not as a painter but as a builder of unique and beautiful clanks), and even then only the names indicate a connection.
 * The Secret Blueprints states that the divergence point was the development of science itself - in our timeline, it was a series of itinerant hiccups until the Industrial Revolution; Hero of Alexandria's steam engine was suppressed by conquerors who didn't want to give up slaves, Leonardo da Vinci's work was suppressed by an ignorance-enforcing Church with the power to burn people alive and claim their possessions. In the GG verse, the instant SCIENCE was discovered, Sparks seized power from warlords and demagogues.
 * "West Pole" makes little sense in our world. Even if it's in the Show Within a Show, their planet must have something different. Or the pole is defined by a field which doesn't exist in our world.

Web Original

 * The Global Guardians PBEM Universe is Present Day Earth plus mutants, magic, sentient apes, intelligent robots, aliens, demons, superheroes, supervillains, high technology, and pretty much anything else that can be dumped into it by way of the Rule of Cool. There are about a dozen places that a person could technically point to and say "that's the divergence point", but the truth is that the universe is just different from ours.