Small Secluded World

The character(s) live in a small secluded world. It could be a Pocket Dimension, a island without communication with the outside world, a spaceship lost on the void, a special kind of prison, or something else that has the same effect. If there is any contact at all with an outside world, then this contact is very limited.

When there doesn't seem to be any world outside the Small Secluded World, then this trope overlaps with World Limited to the Plot. If there is an outside world, characters who grew up secluded from it are very likely to be naive to it. They might mistakenly believe themselves to understand their world -- be Ignorant of Their Own Ignorance. Alternatively, the characters are completely unaware that there exists an outside world at all: there's only the City in a Bottle.

In any case, living in such narrow boundaries is likely to affect the characters negatively. They might get depressed, desperate to get out, or even fail to comprehend that anything larger then their Small Secluded World exists.

May often have a Wall Around the World. Any Hidden Elf Village or Ominous Floating Castle is likely to qualify for this trope if the characters are forced to live there for a while. Also, any case of Ontological Mystery is likely to also be a case of Small Secluded World or World Limited to the Plot, or both.

Compare with Bottle Episode, where the characters are only locked in a secluded world, the bottle, for a single episode.

Comic Books

 * Morbus Gravis takes place in a barbaric world simply called "The City".

Fanfic

 * Most all Harry Potter fanfics portray the wizarding world as such. Harry Potter and The Methods of Rationality is a notable example.

Film

 * In Blast from the Past, the main character is born and lives the first 35 years of his life in a underground bomb shelter. He is raised by his parents, who incorrectly believe that there has been a nuclear war and that the surface has been rendered uninhabitable.
 * Most of The Truman Show takes place in a small society that is extremely secluded from the outside world although the main character is unaware of the artificial nature of the situation (it's all to keep him from ever leaving the fake town where everyone else is a paid actor).
 * Dark City appears to be an ordinary city on earth. But it's actually
 * In Beetlejuice, the main characters are stuck in their house, unable to have any contact with the surrounding world. At first, they do not realize that they are dead and haunting the house in which they lived.
 * In The Others, the main character keeps her children locked in the darkened house due to their genetic disorder which makes sunlight lethal to them.
 * The coffin in Buried.

Literature

 * Room is narrated by a 5-year-old who is unaware of anything outside the 12' x 12' room he lives in. Eventually, his mother reveals that
 * In Flatland, the King of Pointland lives in a nothingness that he mistakes for infinity.
 * In Terry Pratchett's Nation, the main character's world only includes a few islands since no one in his tribe ever sailed far enough to see the continent.
 * Well....
 * Most of the places in The Little Prince, if the story is to be taken literally at all.
 * For most of Robinson Crusoe, the title character is stuck on a deserted island.
 * Lord of the Flies feature a group of teenagers stuck on a deserted island. Unlike Robinson Crusoe, they quickly go wild instead of building a new little civilization.
 * The Greene tribe in Non-Stop are familiar with the idea that they're living in a Generation Ship, but they generally mock it, considering the ship to be all of existence.
 * The generation ship in the short story Paradises Lost. Communication with Earth is infrequent, difficult to understand, and has been known to fail for years at a time. Most people simply don't pay any attention to it at all. It gets to the point where the religious sect Bliss bases its entire system of belief on the conviction that there is nothing outside the ship at all.
 * The exiled brother and sister Ged encounters on a small island in A Wizard of Earthsea. They were marooned on the island as small children, and having spent their whole lives there have "forgotten that there were other people in the world."
 * The City of Ember: The city, but the instructions for escape were lost long ago, and now the city's supplies are running out.
 * In Life The Universe And Everything, the planet of Krikkit has a thick haze covering the outer atmosphere, so it's inhabitants can't even see the stars.
 * In Being There, mentally challenged Chance the Gardener knows no home aside from The Old Man's residence until he is middle-aged and his benefactor's death means he must leave it. He is aware of the outside world, but only through television.

Live Action TV

 * In the Star Trek: Voyager episode "Random Thoughts", the trope is discussed by Seven Of Nine. She argues that the ship ought to seclude itself, in order to avoid the dangers of the surrounding civilizations.
 * In one episode of Star Trek: The Next Generation, USS Enterprise fits in a very disturbing way. Dr Crusher has started noticing that people and places are disappearing, without anyone but her even remembering them. After a while, the starship is all that's left of the universe, and the few crewmen who are left still treat her like a Windmill Crusader for believing that a universe outside the ship ever existed.
 * In Lost, the island usually works so that no one gets in and no one gets out.
 * The Twilight Zone TOS episode "It's a Good Life" takes place in a small town and its environs that were removed from the Earth by a young boy with Reality Warper powers.
 * Possibly removed from the Earth. It's just as feasible that Anthony removed the Earth from around it.
 * Gilligan's Island: the island that Gilligan and the others never seem able to leave.
 * Wonder Woman TV Series: The amazons claim Paradise Island is this: the youngest of these immortals have never seen a man before. However, Princess Diana recognizes a parachute, and the Queen can read Trevor’s english written documents without any problem.

Western Animation

 * Played for laughs and slightly subverted in the Pixar Short "Knick Knack"

Video Games

 * Kingdom Hearts has numerous worlds which exemplify this trope. According to the backstory, travel between them was impossible until Ansem's tomfoolery and the discovery of gummi blocks. From any given world, all the others appear only as stars in the sky.
 * Cocoon from Final Fantasy XIII. It's "only" the size of North America. Most, if not all, of the people of Cocoon have never even glimpsed the world of Gran Pulse below  and have been raised to believe that it's hell. Given all of the horrible monsters that live there, they're not entirely wrong.
 * The Myst series is all about exploring Small Secluded Worlds.

Real Life

 * Isolated lighthouses, back when they weren't automated and there was no radio communication. If the lighthouse was on an island off the coast, the keepers had to stay on their own for weeks or even much longer.
 * Easter Island became this trope for its natives, after all the trees were gone and boats could no longer be constructed to leave.
 * Bluewater sailing on a yacht. A transoceanic leg may take weeks, perhaps months. Before the solar panels and wind turbines, electricity (and hence communication) was on very short supply.