Space-Filling Path

No, you can't just walk from point A to point B. Sorry.

Video game developers don't like wasting space, especially if you're talking about an Adventure Game, RPG, or sometimes a First-Person Shooter. Empty rooms with wide open spaces, especially in dungeons, can be both boring to the player and evident of the developer's laziness. So, what's a developer to do? Easy: Put something in the room. Something—anything—to make the room feel more "substantial".

Sometimes this can lead to very good things, like creative puzzles or miniboss battles.

Other times, it can take a slightly more unfortunate turn: If the developers actually are lazy and can't seem to think of anything to add to the room in question, they'll fill it with obstacles, barriers, and line-like walls whose only purpose is to make the player spend more time in the room. It can also happen if the developers think that these are good things, but they don't actually turn out to be fun.

Another reason may be to delay the player to allow the game more time to load in the background. Staying in control, even if it's to do nothing important, is better than a loading screen, right?

Unfortunately for you, it means that even though that next door is two inches away from you when you enter the room, you're going to have to walk all the way around through the entire damn room in order to get to it. But all hope is not lost: If you're lucky, completing the path once will open a Door to Before.

Here are some of the forms that the Space Filling Path can take:

Ping Pong Path: This is the most basic form of the useless space-filling path. It starts out like a normal old path, but then (for some reason) it curves, making you walk back. And forth. And, if the mappers were feeling especially friendly, back again. Usually (if you're lucky), only two or so iterations are necessary.
Velvet Rope: A cousin of the Ping Pong Path, except much longer and more complex. It relies on the same back-and-forth pattern, but starts to add corners, spirals, and other shapes to better utilize space. It can't really be called a maze, since it usually only contains one path that never branches off, in which case it is technically a labyrinth. Anyone with eyes can see how to get through it, but the question is, who has the patience to walk over nearly every tile in the room to get to the exit?
Intestinal Tract: A Ping Pong or Velvet Rope path with a twist: Instead of just making you walk farther, it also hurts you in some way. How about the occasional Random Encounter as you're trekking through the path? Or perhaps the floor damages you with every step? Sounds fun, doesn't it?
Q*Bert Floor: You have to step on every tile, usually in one contiguous line without retracing your steps. Like the Velvet Rope, only with no visible boundaries. A brilliant source of Guide Dang It, and if there are enemies in the room that knock you around, it might even become That One Room.

Remember, however, that Tropes Are Not Bad; there are many legitimate uses for this trope, though like any trope it still requires restraint.

In FPS games smaller space can be made to look larger with a high density of terrain features and cutting short line of sight, which also allows occlusion culling to reduce the rendering load. This also has the benefits of providing shelter and places to hide.

Some maps in Real Time Strategy games are built this way, in single or multiplayer, to create a long stretch of land to fight over without making a long, skinny map. Also, it creates a more obvious advantage for things like indirect-firing artillery and air transport, both of which can take a shortcut.

This is common in RPGs, as having a longer path means you have to face more Random Encounters without increasing how often they appear.

When combined with Nothing Is Scarier or Empty Room Psych a short space filling path can be an effective horror tool, building suspense without exerting player resources. Though as those tropes note, doing this too much or too often will dampen the effect.

Scenery Porn can take the edge off of this, possibly resulting in a Breather Level.

Examples of Space-Filling Path include:

Baldur's Gate: The third-to-last area is basically nothing more than a large room, with flimsy wooden walls set up to create a labyrinth. There are also several nasty monters who will shoot at you with flaming arrows. Oh, and there are traps set right in front of the monsters, too. And said monsters are resistant to most ranged weapons. Yeah.
Shadow Hearts has done this a few times. The Wine Cellar in Covenant, for example, sends you through several rooms where you have to flip a switch to lower a path to flip a switch... The last switch in a room, thankfully, lowers the path back out.
ZZT games from the earlier years of the program made by first-time designers suffered from the presence of Ping Pong Paths so often that they have appeared in "help" games describing and depicting what not to do in a ZZT game.
- ZZT Syndromes did it particularly memorably, effectively forcing the player to step on most of the tiles on the screen - or it would have if the narrator didn't let you off the hook by carving a tunnel while you were doing it.
Eternal Darkness does this, especially the damaging-floor variety, later on in the game. Why was the whole main lobby of the final dungeon a giant bug zapper again?
Many outdoor locations in Neverwinter Nights 2 are like this—see this map for an Egregious example.
Final Fantasy X and its sequel suffered from this in Macalania Woods and the Mount Gagazet trail, which both featured elongated spirals, where you could actually see the path below you, and in X-2's particularly bad case, you actually do once jump down to the lower path to complete a quest, but can never again use that shortcut.
Most dungeon crawl missions in Warcraft III and its expansion.
- As well as their ancestors, the installation missions from StarCraft.
This is the sole purpose of the genre of web games known as Tower Defense games - you defend a Space-Filling Path from a stream of oncoming Mooks by building defence towers to shoot them. In some instances, you must also create the SFP, which is an added problem/puzzle. Usually, you must create it while the enemies are flowing, which is even more difficult.
The world map of the first Dragon Warrior game arguably fits this trope, as the final enemy's castle is visible from the starting area, but requires a circuitous route to reach.
Wolfenstein 3D had loads of these. E3M8 is particularly bad. E6M8 is infinitely worse (imagine a figure eight, with paths filling in the insides of both loops).
A map in Star Wars: Jedi Academy starts with you about to walk from a landing to platform to a nearby building... but then the bridge is blown up by your target. Cue a level which requires you to go through all the surrounding skyscrapers just to reach the one you intended to enter.
ROM hacks (especially of Super Mario World) and Nintendo Hard platform games are the kings of this, utilising both the ping pong path and the velvet rope path to near ridiculous degrees to make sure every possible part of each room is filled with more and more narrow jumps and instant death spikes. And in some even worse cases, you have to go right back through said maze with an item or after an action is taken the other side.
Nethack is guilty of this, to a certain extent - the deepest levels of the game are completely maze-like, and delay moving from one floor to the next to an aggravating degree... although this is why savvy hackers will just bring a pick-axe with them.
- This is why savvy hackers have Teleport Control. But really savvy hackers bring both, because teleportation becomes unreliable once you have the Amulet.
- The variant Slash'EM has a guaranteed Ping Pong Path on one deep level... it's less about filling up space, and more about giving the Wizard of Yendor plenty of time to lay his ubiquitous brand of smackdown upon you at his leisure.
Dungeons in the game The Elder Scrolls II: Daggerfall have been described affectionately as octopi mating and the random generator is not even entirely to blame for this. Even some of the main quest dungeons, which were carefully designed, appear nebulous.
Metroid Prime 2: Echoes has a number of rooms where there are two doors, one of which is always blocked by a rotating barrier. To rotate the barrier so you can access the other door, all you have to do is place a Morph Ball Bomb in the slot. Of course, now the barrier is on the first door, so you have to do it AGAIN in order to get back. This gets really, really tedious as the rooms are otherwise completely pointless, and you will generally visit them several times.
This is the idea behind real labyrinths (as opposed to mazes), such as the Labyrinth of Chartres. It is meant as a metaphorical or meditative activity.
Devil May Cry 1 and 3 both have examples of this trope. In the first game, there's tentacles trying to get you while in the third game, there literally is an Intestinal Tract.
At a certain point in Timeshift you enter a fucking enormous warehouse, so big it constitutes the entirety of the level. You're standing on a metal gangplank overlooking a deadly drop, and the exit point is... straight to your left. Unfortunately, inbetween you and it sit a few stacked boxes. You look at them and go "ok, there's a small space I should realistically be able to jump on to bypass them", but no, if you try that you fall and die. Then you think "why can't I climb them or push them off?", but no, jumping and the action button have no effect (neither does, of course, shooting them with a rocket). The only possible course of action is to go the other way, and start on a ridiculously long and convoluted path that will take you across the entirety of the warehouse - both on the ground floor and on more gangplanks than can be counted - before ultimately leading you to the exit point.
Since every room in Lufia 2 has a puzzle, there are quite a few room with the aforementioned Q*Bert floor.
Star Fox Adventures contains an underground maze which, while not difficult to figure out, must be visited multiple times in the course of a playthrough to help pad out the length of the game.
The paths towards both the last town and The Very Definitely Final Dungeon in Sword of Vermilion are examples of this trope, the first being a long spiral and the second a long back and forth winding path. One villager even lampshades it, saying that the Big Bad made it that way to "discourage you".
Jet Force Gemini. Multiple levels must be revisited to collect every single one of the furry innocent civilians. Who are very vulnerable to any enemy fire. So blow five minutes blasting through yet another reiteration of the same level and a giant rocket blows Squishy Chewbacca to kingdom come? Start over, man. And the pathways through the levels cross over and loop and wrap around each other in dozens of various and differing ways. All not accessible all the time because of various abillities of the three main characters. Long story short, you're going to be seeing the same engine room a LOT. And yes, the enemies will always respawn.
The Q*Bert Floor is used extensively as puzzles in later handheld Zelda games.
The Armory wing in World of Warcraft's Scarlet Monastery consists largely of a pair of massive hallways with gates arbitrarily placed to maximize the time needed (and the number of enemy groups encountered) to traverse it.
- Most of the dungeons invoke this trope, the ones in the expansion packs just tend to be smaller.
- The most trope-fitting being Razorfen Downs, with the last 45 minutes spent climbing a tacked-on ascending spiral ramp.
A pet peeve of many Mega Man Battle Network players is long, twisty paths in areas of cyberspace where there's no reason for it. Or rather, there is a reason—the designers are forcing more random encounters. It's especially annoying the way each game's final boss has a long enough runup that you'll get attacked at least once, and this is after the no-save point.
- In the sixth game, Green Area is an Egregious form of intestinal tract. The stage of the Green Town boss, Judgeman, is also a good example of the Q-Bert Floor.
Chrono Trigger DS. Lost Sanctum. Not only is it a Space-Filling Path, but you have to go back and forth on it over and over until you die of boredom.
Pokémon Ruby, Sapphire and Emerald had a Q*Bert floor in the 8th gym, where if you stepped on the same tile twice, you fell through the floor into an intestinal tract of trainers.
- And there is another Q*Bert set on Sky Pillar, this time you need to use the Mach Bike which is pretty fast but hard to maneuver, if you walk over the cracked tiles normally or stop (like failing to turn with the bike at the right time or not going at full speed) you fall to the previous floor.
  - And various in-game pop-up messages like hatching eggs, poison fainting pokemon or repel's effects wearing off will stop it...
Titan Quest has a velvet rope path in the Labyrinth of Minos.
Super Mario Bros. has this with the block trains/snakes in some of the castles in Super Mario World, New Super Mario Bros and quite a few Mario World hacks, which have Mario riding a moving train of blocks that pretty much goes the long way round a huge room past a ton of obstacles. New Super Mario Bros even had one in one of the tower levels which went right, up one block, left, up another block, ad nauseum for a while before moving on upwards.
The infamous Golden Gun Room in Golden Eye 1997 features a Q-Bert Floor. Step on the wrong tile, and the automated gun turrets will turn you to Swiss cheese.
Many levels in the Halo series follow a ping-pong or velvet rope space-filling path, sometimes enforcing this with instant-death fall barriers. Examples include Pillar of Autumn, Truth and Reconciliation, Assault on the Control Room, Keyes, Delta Halo, Uprising/Great Journey, Sierra 117, and Tsavo Highway. Often, these are used to facilitate Dynamic Loading. The Library and its descendants are Intestinal Tract levels with constant Flood ambushes and other hazards. And the infamous "Cortana" mission is a near-literal intestinal tract, complete with "sphincdoors".
I Wanna Be the Guy has countless "intestinal tract" type rooms, including several chock full of Spikes of Doom (eg the Room of Patience, which also has four Lifts of Doom), a gauntlet of Quick Man Death Rays, and a path consisting of a "snake" of Temporary Platforms that gradually increases in speed.
Most of the levels in Winback consist of space-filling paths, usually "ping pong" paths, sometimes with Back Tracking through parts of previous levels.
Ultima 7 part 2. One of the (many) trials in the game is a snaking path filled with acid. Plot-wise, you have to recruit an acid-immune character to bypass it, although bringing along a load of healing potions also works.
Wizardry V. Dungeon level 4. It does warn you that a 'Labyrinth of Doom' is ahead, or something to that effect. If you don't listen, expect to have to traverse a wind about, single tile path filling half the dungeon and containing nothing but enemies with all sorts of Standard Status Effects including poison, petrification, and instant death. Of course there's a secret door to skip it right at the entrance...
The Chronicles of the Sword section of Soul Calibur 3 had a lot of ping-pong paths. This is made more annoying by the space between the paths frequently being lawn or other terrain that should be entirely traversable, but you still have to take the long route.
Brandish lays out the routes on each floor so that you end up covering nearly all of the square-shaped map screen just trying to go from one staircase to the next. There are a few side rooms here and there that you don't need to enter unless you want some extra items, but if you end up trying to backtrack to a previous floor, you're going through nearly the whole map again.
Arcana for the SNES has plenty of winding paths or long dead-end corridors that seem to exist only to give you more chances of getting into a random battle. Especially since simply making a 90-degree turn has a chance of ending up in a battle, just like taking a step forward or backward.
The 2-D Zelda games usually had at least one dungeon with a Q*Bert Floor room. Some even had ping-pong paths, but usually averted as getting the Roc's Feather would allow you to jump quickly across the path.
- The overworld of The Legend of Zelda a Link To T He Past had plenty of tree clusters, fences and one way ledge jump off points, among other things, that limited travel pathway options, forcing roundabout routes to nearby destinations.
This is one of the reasons the Water Temple from The Legend of Zelda Ocarina of Time gets a lot of hate. Not only do you have to submerge yourself and run (rather slowly at that) through underwater tunnels and resurface, but you also have to constantly switch water levels at designated checkpoints, each one corresponding to a particular tier. Much Back Tracking abounds, especially if you alter the water level incorrectly for the current situation.
Castlevania: Harmony of Dissonance has many zigzagging paths designed to make you abuse your two-way dash move just to save time.
- The first GBA title, Circle of the Moon, was pretty obnoxious as well. In any room that was more than one screen wide or tall, it was virtually guaranteed that you'd move through every possible screen to get from one corner to the other.
  - No mention of Castlevania: Symphony of the Night? It was notorious for all of this. Thankfully by Aria of Sorrow, IGA and company wisely started consolidating the castle designs and expand the number of warp spots from then on to reduce all of that needless backtracking.
Valve tends to do this in rather subtle and creative ways.
- In Half-Life 2, Ravenholm seems a lot larger than it really is, as the player must traverse the streets, building interiors AND roofs.
- On a similar note, Portal has Test Chamber 17, in which you can see the button that you place the Weighted Companion Cube on towards the end of the level through a glass floor in one of the energy ball hallways, as well as through a window in the main room.
- Left 4 Dead 2 also has a couple examples. You can see the Safe Room in the Barns chapter of Dark Carnival about halfway through the level (and you can throw Gnome Chompski over the fence if you have him). However, to get to it, the Survivors must continue past said fence, turn around and fight through some barns running alongside the area they just navigated, climb on top of and traverse the roofs of those same barns to reach the other side of the fence, and then fight through a continuous onslaught of zombies.
  - The Crescendo event in the The Park level of The Parish has the players running through what used to be a waiting queue; as such, it is a little less subtle.
- The entire level of Dead Air (from Left 4 Dead 1) is this.
In Super Mario Galaxy, Luigi's Purple Coins becomes a Q*bert Floor, as every platform that it is safe to stand on either disappears or starts rotating and becomes unstable after touching them.
- There is also, the Hurry, He's Hungry Star in the Sea Slide Galaxy as well as the Shrinking Satellite star in the Hurry Scurry Galaxy, which features a planetoid constructed completely out of disappearing tiles with a Black Hole in the center. Mario must grab an item from each tile, at which point the black hole turns into a Star.
- In Super Mario Galaxy 2, the Cosmic Clones are a Q*bert Floor mechanic to an extent, because you to have to run from infinite numbers of Mario clones that copy your every move and crossing your path leads to being hurt via Collision Damage. This gets applied then to Luigi's Purple Coins from the first game... This time, though, you have Co-Star Luma (if you have friends) to stop the green tiles from disappearing.
Many StarCraft and Starcraft II multiplayer maps feature a long, twisty route from one end of the battlefield. Generally, air-heavy strategies are more practical on these maps, since the greater mobility of aircraft helps cancel out the increased time to get to them in the Tech Tree. On map from SC2 in particular is the epitome of this trope in RTSes - the players' starting locations are on separate plateaus arranged in a circle, with ramps down to a ring around the exterior of the map - the only ground route available.
Nier has one of these when you go to the Warm Up Dungeon where you have to follow a ridiculously looping route to bypass approximately 20 feet of collapsed canyon, which contains no enemies, puzzles or loot and appears to exist for the sole purpose of a cut-scene pan across the tower.
Breath of Fire has a major one. The path appears to be simple—just a bridge with a few extra paths veering off of it... until you step on the button that spins the screen and the characters until you don't know which way is up. And since its nothing but blackness all around, you can't even use landmarks. Even on the straight stretches you can find yourself turned around and going back the way you came.
While most of Dragon Age: Origins is railroading at its finest, the most annoying part is the Gauntlet, where you have to keep moving characters in a certain sequence in order to unlock the next part of the puzzle to get The Sacred Ashes of Andraste.

Non-Video Game Examples

Some cathedrals have a space-filling path marked on the floor, apparently so that pilgrims can walk a long distance inside the cathedral without retracing their steps.
- "Walking the Labyrinth" is part of Lenten devotionals in many denominations, sometimes associated with the Stations of the Cross.
Every theme park in the world uses this to fit as many queueing people as possible into as small a space as possible.
Also banks, fast food, some stores (by the registers), boxes for linked-belt ammo, cooling conveyors in food production... basically, any time something needs to be stored for a time while remaining in first-in-first-out order.
- Many grocery stores were retrofitted in 2020 to have Space-Filling Paths through their aisles, in order to keep people from going in the opposite direction to the flow and messing up everyone's physical/social distancing during the pandemic.
Switchbacks on mountain roads. In this case, artificially lengthening the road allows the grade to be less steep: it's rise-over-run, and rise is fixed, so beef up "run".
- A few streets in especially hilly cities do the same thing for the same reason, such as one block of Lombard Street in San Francisco.
In demolitions, time delays are added for synchronizing charges by inserting bundled loops of detcord into the fuse lines. A coiled bundle about 4000 meters long will delay the signal by a half second: it burns very fast.
Many cities before urban planning developed in this manner, with complex and densely-packed structures around narrow roads and alleys. Papal Rome in particular developed what had been a fluke of development into a symbol of revelation, pilgrims to the See passing from the darkness of these roads into the brilliant light of Saint Peter's Square and the heart of the Catholic Church. Mussolini then controversially demolished most of the neighbourhood, as well as destroying or relocating many historic buildings and residences, in order to create a straight path as part of his general renovation of Rome. The Via della Conciliazione remains disliked even today for this.
There's a special term for any labyrinth that doesn't branch: Unicursal. Every unicursal labyrinth, incidentally, is a space filling path by design.
Space-filling curves are continuous curves that nonetheless fill an entire square. They are used to provide useful examples/counterexamples to many topological statements. For examples, they explain why the notion of dimension is more complex than it seems to be. Versions of them are also often used in computer programs for geospatial data.