Disconnected Side Area

In video games, normally one expects all playable parts of a level to be reachable from one single point. It might not be a point you can get to without unlocking a whole bunch of things and even Back Tracking from later in the game, but it still ought to be there.

But sometimes, you just can't get there from here (or here from there). You've found a side area that is ostensibly part of the level, perhaps even can be seen from other parts of the level, and in fact playable (not just for show), but you have to go around (often a long way around) to get between. The more infuriating of these are located behind an Insurmountable Waist-Height Fence. On the other hand, you may find an area early on in the game that gives you a sneak preview of a much later level. Or there may be a Door to Before that leads back to the main area.

Some may be genuinely unused, yet have more functionality than required for decorations just because that's how the level editor works. Those may fill the space for no other purpose than an illusion of the game world being larger and more complex that it is. Or could be partially Dummied Out into non-interactivity as content made for removed plot lines or not implemented properly in time, but looking too good to throw out.

Randomly Generated Levels often end up like this, though few generators are bad enough to make places inaccessible rather than merely twisted.

Another possible technical reason is data file economy: levels are often implemented as large arrays of tiles and connected by (usually implicit) teleport event triggers; and even 3D maps may have a significant overhead of map-wide data… so developers simply cram together into a single map sheet a bunch of fragments too small to use up a whole level; it's more common with enclosed areas like towers and tunnels, however — those you won't see in the game, except via auto-map sheets and glitches.

Common in Metroidvania style games and some RPG titles.


 * Banjo-Tooie likes to put Jiggies in these side areas, though other items are hidden here as well. The game isn't consistent about which Jiggies count for which levels: one of the Jiggies counting for Hailfire Peaks has to be reached from Terrydactyland, while another is in a side area of Grunty Industries. Yet another Hailfire Peaks Jiggy is in an ice cave that doesn't connect to anywhere else on the Icy Side.
 * La-Mulana, among other disconnected side areas, has a side area of the Chamber of Extinction leading to a side area of the Surface leading to a side area of the Inferno Cavern.
 * Crash Bandicoot 2: Cortex Strikes Back was horrible with this. Most levels were perfectly linear, but there were all sorts of level segments that were blatantly impossible to get to from their respective levels. You had to find secret elevators from other levels and eventually the secret sixth hub room in order to get to them, rendering 100% Completion for those levels (breaking all the boxes) impossible until very late in the game.
 * The Metroid Prime series is pretty bad about this a lot of times, too. A notable example is in the second game where there's a portal and blue door right off the central room of Agon Wastes, which nags you as something you missed every time you look at the map. But it's sealed off by an impenetrable gate both in the light and the dark world. It turns out that this particular section of the map is only attainable much later when you have the proper gear, and takes a veeery long roundabout path to get to. Most players even get there via an elevator directly from Torvus Bog followed by a one-way dark world portal.
 * The 2D Metroid titles have this sometimes too. Super Metroid has a few areas partially visible before you can fully access them.
 * Super Mario 64 has a partial example in Wet-Dry World. The "town" section is isolated from the rest of the level, uses a separate set of water controls, and can only be easily accessed if you enter the level in a specific way - otherwise, you need to make a relatively difficult cannon shot. Also, though Eyerock is nominally in the same area as the rest of the pyramid, it is sealed off from the rest of the pyramid and has a separate hidden entrance that is needed to access it.
 * If different characters have the same level in Sonic Adventure, they will frequently cover completely different parts of what is nominally the same place. For example, Tails and Knuckles both go to Speed Highway, but their game areas are completely different (and sealed off from one another).
 * Sonic usually will visit a given level in its entirety, though there are occasionally areas that are off-limits to him and designed for someone else (like Twinkle Park's mirror rooms.) Amy takes over Sonic's role in doing this on the level Hot Shelter, the only one in the game Sonic doesn't visit. She runs through the entire level, while Big goes through the first few rooms and Gamma most of the rest.
 * Big the Cat can see Sonic's path in Emerald Coast (and Sonic can see parts of Big's fishing area), but Big can't go up the slopes and get to Sonic's part of the level, and a gust of wind prevents Sonic from falling down to Big's area.
 * In Red Mountain, Sonic can see tall pieces of rock in the distance (and they're not just for decoration), as well as some floating item boxes and a few items on ledges, but only Knuckles can access these things.
 * Tails can see parts of Windy Vally that can only be accessed by using Light Dash - a move that only Sonic can use (and he can only use that move once he has the Light Speed Shoes, which you find on the way to the level that Sonic goes to after this).
 * Knuckles can see the doors to the slot/pinball and card/pinball games in Casinopolis, but only Sonic can go inside those doors. Similarly, every character can see the switch for opening the door to the Hot Shelter, but only Amy, Big and Gamma are ever allowed to go inside.
 * Rayman 2 includes a few level segments that aren't even accessible from the same level: about 20% of the second level in the game is only accessible through a level that doesn't appear until past the halfway-point.
 * One Wraithheart in the Summit of the Sages in Vexx is hidden away in a strange, floating net connected to a pipe. The only way to get it is to literally go Down the Drain in a different level, Tempest Peak Manor, which drops you there.
 * That's not all in Vexx. In the second level, one of the hearts is hidden in the "Sand Castle," which only appears in the level as a literal sandcastle that's too tiny to do anything with. You have to go halfway through the Toy Castle in the first level, hit a hidden switch, and THEN you'll end up in the Sand Castle, which is just a Palette Swapped Toy Castle after all.
 * The Donut Secret 2 and Chocolate Secret levels in Super Mario World are located on the Valley of Bowser map. They are not connected to any of the other levels there, and have to be reached by warp pipe.
 * The Avernum series does this a lot, at least in part 4 and 5. There are rooms you can see fairly early in the game, but you can't actually get there until you've moved all the way around.
 * In the Paramina Rift in Final Fantasy XII, there's a frozen lake, which at one point has a huge gap in the ice; you can see the other side, but you have to go around to get to it.
 * There's a few in the Dalamsca Westersand, too; one of them is used to hide one of the keys to a Bonus Boss. And some places in the Garamscythe Waterway can't be reached because there's some inch-deep water separating two platforms which are, at best, a foot away from each other. It is sufficient to say that this occurs frequently.
 * There's also the section of the Nam-Yensa Sand Sea (or the Sand Sea right next to it, near Raithwall's Tomb) that can only be reched via a specific path in the Zertinian Caverns. There's a very fun Mark Hunt that takes place in that area, but it can be a huge pain to figure out how to get there (Lampshaded by the hint they give you to the location of the Mark as being isolated and hard to find).
 * Final Fantasy X-2 takes advantage of this phenomenon by giving Yuna the ability to jump, allowing her to surmount certain waist-high fences to explore new parts of areas from the first game.
 * In Pokémon Red and Blue (and, naturally, FireRed and LeafGreen), once you get to Route 2 you may notice an inaccessible area on the other side of the line of trees. This area is first accessible only as an extension of the Diglett Cave dungeon until you obtain the Cut HM and get the corresponding badge.
 * There's several of these, especially in the early games. West of Viridian City is the path to the Pokémon League, but until you reach the end of the game it's just one of these. And in Gold and Silver, you can surf east of the starter town to cross the Kanto border, but without Waterfall you can go no further.
 * Also in Red and Blue, at the bottom of Pallet Town is a small lake that leads off the bottom of the screen. If you remember to come back after getting Surf (and the corresponding badge), the lake opens up into the ocean, leading to a small patch of grass (the only place where you can catch a Tangela) and Cinnabar Island (the second-to-last gym battle).
 * In Gold and Silver, there's a tree blocking the way for easy access to Goldenrod City from Violet City. The solution to make the tree go away? It's in Goldenrod City, through which you have to take a long detour through caves and a forest.
 * Also, in Gold and Silver, the Silver Cave is visible on the Town Map from the very beginning of the game, but without any discernible paths leading to it. It becomes reachable at the very end of the Playable Epilogue, and requires the player to travel through a second region in order to reach it.
 * Milons Secret Castle has a room within the first room that taunts you with a large stash of money. The room is only accessible once you reach the third floor of the castle.
 * Etrian Odyssey loves this trope, with large disconnected hidden paths back and forth through the levels.
 * RuneScape had a small island only a couple squares from the beach of Catherby. To get there, you have to travel across some mountains and then through a long and difficult underground dungeon.
 * Cave Story's Labyrinth camp area has a room with a treasure chest in it. The only way to get there is to go through the hidden passage outside blocked with a breakable block.
 * Kingdom Hearts has Space Paranoids, which can only be accessed by using Ansem's Computer in Hollow Bastion.
 * Descent has many secret rooms that are visible behind a grate from the main level, but are only accessible via well-hidden doors halfway across the map.
 * The Swamp of Evil in The Legend of Zelda a Link To T He Past, which has to be visited to complete the game due to the fact that it is the home of the Misery Mire dungeon, is walled off from the rest of the Dark World map, and can only be reached via a warp tile in the Light World on a cliff that you need the Warp Whistle to get to, and said cliff happens to be a case of this trope to the Desert of Mystery in the Light World.
 * Used again in Ocarina of Time with the Shadow Temple, which can only be accessed with the ocarina warp song because it's located on a ledge which cannot be climbed up.
 * The Bottom of the Well seems to be this to the Shadow Temple itself.
 * And the Spirit Temple, the first half of which you must enter as Child Link to obtain the item to access the Adult Link half of the dungeon.
 * And again in Oracle of Seasons... three times. Part of Hero's Cave can only be accessed from an alternate entrance, and then the Snake's Remains level has one area walled off from the rest, which has to be accessed by exiting the dungeon through a separate entrance and re-entering through yet another one. Finally, the Tower of Spring is walled off from the rest of the Temple of Seasons and must be accessed through an underground passage.
 * The Skull Woods dungeon in A Link To The Past consists of three disconnected areas only accessable from different above-ground entrances in the Skeleton Forest portion of the Dark World's overworld.
 * More examples in A Link To The Past are the second half of the Desert Palace (which happens to be located in the above-mentioned Desert of Mystery), accessed by a separate entrance on the cliff above the main palace, and two of the Heart Pieces on Death Mountain.
 * In Twilight Princess, the Gerudo Desert cannot be reached on foot like every other land-based area and must instead be traversed to with a giant canon at Lake Hylia. The only way to get out of the area is to warp out.
 * Quake II has several of these. The second half of Installation is only accessible via Door to Before from the Comm Center, and the Drilling Area has an isolated area only found through a secret door in the Borehole. Same for Quake IV, which sometimes uses the "later level preview" type.
 * Rygar for the NES has an impenetrable wall at the beginning, beyond which you can see a much later part of the game.
 * In Sonic 3 and Knuckles the second acts of Angel Island, Marble Garden, Lava Reef, etc. have disconnected alternate paths only accessible by Knuckles through otherwise unbreakable walls in the first acts. Ditto for Sonic 2.
 * Similarly, Knuckles' low jumping height is used to bar him from places only Sonic and\or Tails should go. Ledges prevent him from just climbing up.
 * The TRS-80 Color Computer Platform Game Downland had alot of these.
 * Non-video game example: For the longest time, Disney's California Adventure (due to construction on a new Cars-themed area) had required you to walk through the Flik's Bug Land area to reach the Twilight Zone Tower of Terror. There was no other way to reach the tower, but construction has now progressed enough that you can reach it through the Hollywood Studios land on the other side.
 * Occurs frequently with buildings under construction.
 * Many buildings have areas that can only be accessed by the public via certain elevators, as the doors to said area from the rest of the floor are locked from inside. Such as the second floor area behind the Child Life playroom in Seattle's Children's Hospital.
 * Spencer Island Park in Everett, WA used to have a loop trail going all the way around the island, but a dike fire in 2004 destroyed part of the trail, and due to erosion problems and maintenance costs, it hasn't been bridged, forcing you to cut across the middle dike to get back and to the other half of the trail. For a while, the south loop was also disconnected due to the collapse of the cross-dike.
 * One of the University of Washington's buildings has a library only acessible by elevator, no stairs. If you're stuck up there in a power outage, god help you.
 * In F-Zero, in addition to having two different music themes, White Land is unique in that its second track is not connected to the first track.
 * In Halo 2's Delta Halo, you can see the buildings from the next level, Regret, fairly early on, but unless you find a hard-to-reach shortcut, you'll be going the long way around. Similarly, at the beginning of Uprising, you can see the area where The Great Journey takes place, but the only way down is through a long Space-Filling Path, and there are no shortcuts this time. High Charity consists mainly of previously inaccessable side areas of the previous level, Gravemind, which were also visible in earlier cutscenes. Earlier, the Banshee combat sequence at the end of The Arbiter gives you previews of the outdoor parts of The Oracle, the next level.
 * The only way to get to the library area in Resident Evil is to take the elevator from the basement, unless you get the passcode from Barry as Jill. This bypass is in fact required to get the best ending in that scenario.
 * The sewage disposal area in RE2 is only accessible through air ducts, as the doorway in is shuttered.
 * This trope occurs throughout the series in spades. Some areas don't even appear on the map until later.
 * VVVVVV has a few of the "sneak previews of a later level" variety:
 * In Space Station 1 (the very first level), there's a series of rooms where you can only reach the top half of each room, even though you can see the bottom halves. Later, the Space Station 2 level goes through the bottom halves of those rooms, many of which have harder versions of obstacles from their respective top halves.
 * One of the computer terminals you come across throughout the game mentions a sealed-away secret laboratory, which gets marked on your world map. Another room in the overworld (along the path to the Warp Zone level's entrance) has a side path which leads to a little alcove on the side of the Secret Lab, which lets you see one room of the lab but doesn't actually let you in. But if you get One Hundred Percent Completion
 * In the 1998 FPS Sin, the "preview" of later levels is played in a very interesting fashion. In certain levels, exploring long enough will yield access to rooms that can be seen (but not accessed) in later levels. In addition, most of these disconnected side areas have a feature that you can use (whether it's pulling a switch or disabling an object) that will benefit the player when they reach the later level. For instance, climbing through the ventilation system in the SinTEK Office level will net you access to a control panel located just above the building's main vents; destroying this panel makes the section where you have to climb down through spinning fans in an underground laboratory much easier.
 * In Silent Hill 2, the east wing of the Hotel's first floor and most of the basement are only accessible via a service elevator that requires you to leave all your belongings behind. At least until you unlock the Door to Before. This trope occurs in spades throughout the series.
 * In Monster Tale, the last area has warps to disconnected side areas in each of the other four areas.
 * In Space Quest II, you can see the second floor walkway from the moment you enter Vohaul's asteroid fortress, but there's no elevator button for that floor. You'll be taking a long side path to it, solving many puzzles along the way.
 * Bug!! has several of these, mostly because the game is a 3D-ish platformer. In order to get to many of them, you have to do a Leap of Faith (usually into the foreground)- and if you're lucky, you'll land in the secret area.
 * Dynasty Warriors is rife with this, seemingly as an artifact of having all the maps being square-ish in shape. Often a thin row of fences or small river is all that stands between you and an objective, but getting there requires going halfway around the map.
 * Sister series Samurai Warriors actually takes advantage of this with it's "ninja paths". The small handful of ninja characters can use their double jump to reach certain areas too high for most characters, allowing them to take significant shortcuts.
 * In Medal of Honor Allied Assault's Level 4-2 (Diverting the Enemy), the end area is visible through a window earlier in the level, and you can pre-emptively snipe some of the enemies from here. Halfway through level 3-4, you can see the church that marks your objective location behind a barbed wire barricade, but to get to it, you must go through a large graveyard covered by multiple machine guns. As for the objective itself, three of the Nebelwerfers are separated from the first by barbed wire and a minefield, and to reach them, you must run through their line of fire and negotiate an enemy-filled trench.
 * The second to last level of Medal of Honor: Frontline has one of the "next level preview" type at the end. No, you can't climb over the barrier.
 * One of the secret teleporters in Pathways into Darkness's "Happy Happy, Carnage Carnage" level warps you to an inescapable deathtrap room in a much later level. After completing "Who Else Wants Some?", you warp back to a previously inaccessable room behind a Door to Before on "I'd Rather Be Surfing".
 * Some levels of Blaster Master have one-way passages by way of respawning block floors that you can't destroy from above, forcing you to take a different route back.
 * The upside-down ice city of Glacia in Skies of Arcadia has a small section just off to the side from the entrance that can't be reached when you first visit. Shortly after completing the dungeon, your Cool Airship gets an upgrade that lets you fly under the continent and enter the city from below.
 * In Turok 2's Death Marshes, the first ammo storage facility is on a ledge right above the starting point, but is only reachable by a hidden side path much later in the level. One of the prison cages can be previewed on the far side of an insurmountable quicksand pit. The other levels have many examples of this too.
 * The initially visible stairways in Dragon Quest I's Charlock Castle lead to dead-ends. To find the real entrance, you must Search behind the throne.
 * The NES version of Strider, being a Metroidvania-type game, has a number of these, including some only accessible from other levels (e.g., a tube in Australia warps you to a previously inaccessable part of Africa).
 * Variation in Castlevania: Dawn of Sorrow, also a Metroidvania. One of the "maps" you can acquire reveals all the rooms in the Wizardry Lab. Most of the rooms are accessible the first time through, or are clear Doors to Before. But, wait... what's this one section marked out below everything else? Of course, you don't get to that part until much later, if you do at all.
 * Stage 2-3 in Purple has a chamber with a switch to Bonus Stage right above a room with a Check Point. The only way to reach the switch is somewhere in another stage.
 * The passage that leads to the Core of Ys in Ys II is walled off from the rest of the Canals, and can only be warped into by using the Gold Pendant at the warp statues. The later parts of the Solomon Palace are also disconnected and must be reached either by the Canals or teleportation. Earlier, the final priest's shrine in the Divine Area is rendered inaccessable by a mine cave-in, and can only be reached by ringing the Evil Bell in the basement of Jira's house to open a secret passage. In the first game, to pass the "Devil's Wind Corridor", you have to break a pillar on the other side of the outer gallery, which must be reached via a separate stairway.
 * Tomb Raider, especially the third game, has many of these.
 * Real life example: Point Roberts, WA is geopolitically disconnected from the rest of the state mainland and can only be driven to by going through Canada. Even better are Hyder, AK, which is only drivable to by a road from Stewart, BC, and Estcourt Station, ME, which is only publically accessible through Quebec.
 * On a smaller scale, Evergreen Point, a neighborhood in Medina, WA, a suburb of Seattle, is cut off from the rest of the mainland by the WA 520 freeway, and no offramps go to it, so its only road access is by 76th Ave NE.
 * The eastern part of the map in the first King's Quest is cut off by an uncrossable river, so the only way there is being picked up by the Condor. To get back, you must go through a one-way underground passage and shrink yourself with an Alice in Wonderland style magic mushroom. Woe betide you if you go underground without the mushroom.
 * Riven has a number of these. First of all, there's the section of Jungle Island with the Fire Marble Dome and the Wahrk Gallows switch that can initially only be accessed by the gondola on the back side of Survey Island, until you open the Door to Before through the Wahrk Totem. Then there's the latter half of the Golden Dome on the first island, which must be accessed by the bridge from Crater Island. Finally, the fifth island that is isolated from the other four must be warped to through the Fire Marble Dome Portal Network, the hub of which is Gehn's Age.