->''"Steep Slope Barrier - You would know this was possible if you'd ever actually been outside."''
-->-- '''Comic Book Guy''', ''WesternAnimation/TheSimpsons [[VideoGame/TheSimpsonsGame Game]]''

As video games become more sophisticated, their environments become bigger and more realistic ... but they still aren't as big as all outdoors. A developer can easily limit an indoor environment -- buildings have walls. Outdoors, however, there's only so many [[InsurmountableWaistHighFence fences]] a game-developer can put up before every forest looks like some kind of park. A ''gravity barrier'' is either a cliff or slope that's too tall to climb... or a drop that kills the player.

Gravity barriers have the potential advantage of looking realistic without being out of place. Sure, the real world has lots of sheer drops or rocky cliff-sides that might be nigh-impassible to the untrained outdoorsman. On the other hand, as graphics have improved, "mountain ranges" that are ridiculously steep yet not much higher than a three-story building randomly jutting out of the mostly-flat grasslands have come to look less like a plausible terrain feature and more like an AcceptableBreakFromReality... especially when said ranges [[GatelessGhetto completely surround the map like a giant crater]].

The best video-game map-makers can use gravity barriers to restrict player movement, in a way that's not blatant manipulation. A poor game design will use the [[InsurmountableWaistHighFence insurmountable waist height fence]] -- the obstacle that obviously restricts progress but that anyone could just climb over, given the steely determination of a video game hero. A ''really'' bad game design will use the InvisibleWall to prevent a character from progressing further.

Another version of this trope is the water barrier, where a player cannot proceed because a large body of water blocks their progress. Either [[SuperDrowningSkills they will drown]] if they try to cross it, or some form of BorderPatrol (usually carnivorous fish) will stop them from swimming too far out, or the water will continue forever and they will eventually get bored and give up.

Gravity barriers can sometimes be temporary obstacles, until a character comes back with a power-up that provides VideoGameFlight.

The gravity barrier may also be used to allow a player to move forward, but then [[PointOfNoReturn restrict their backtracking]]. For example, a character may leap off a small cliff and fall into a new region, and the cliff behind them is unclimbable. The player knows they've both made forward progress and cannot retreat, because they crossed a gravity barrier.

But if a clever player finds a way to get down the cliff without dying, SequenceBreaking may ensue...

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!!Examples:

[[foldercontrol]]

[[folder:Action Adventure]]
* In ''VideoGame/InFamous'', in which the protagonist accidentally electrocutes himself in water more than a couple of inches deep.
* The ''MetroidPrime 3D'' games used this extensively: either there was an impassable ridge looming high above, insurmountable even by Samus' legendary jumping skills, or a precipice. There was some subtle manipulation as well, in ''Prime 2: Echoes'' and ''Prime 3: Corruption'', where attempting to cross a boundary chasm using the Screw Attack would suddenly eliminate the technique's momentum and drop Samus like a stone. Of course, this is absent in the 2D games, where the Wall Jump and the infinite Space Jump allow Samus to leap over any vertical obstacle.
** The 2D games have their gravity barriers as well, but years of SequenceBreaking have rendered them nearly meaningless. New players who aren't familiar with wall jumping will find plenty of unreachable ledges, often coupled with deep water that kills your mobility upgrades.
** ''VideoGame/MetroidFusion'' puts a twist on the water variant by making it ''horizontal'' as well: until you get the Gravity Suit, you can't use the SprintShoes you'll need to escape a flooded area late in the game.
* The ''Franchise/TombRaider'' series uses these a lot, both to define the outer edges of outdoor levels (unclimbable cliffs) and occasionally to prevent backtracking (slides down really steep slopes).
* ''VideoGame/{{Prototype}}'' has a water barrier. However, while the hero is ''far'' too dense to be able to swim, he can ''jump off the bottom'' just fine. The game has to artificially force the player to jump in the direction of the shore to prevent him from going out of bounds.
* Recent ''Franchise/SpiderMan'' and ''IncredibleHulk'' games have featured these, especially the island-city-and-incidentally-your-hero-can't-swim variety.
* In the ''[[LegoAdaptationGame Lego Star Wars]]'' games, the only way of knowing you've encountered one of these, especially when there appears to be a ledge on the other side, is attempting to cross with an astromech droid.
* ''VideoGame/SpyroTheDragon'' uses [[InvisibleWall invisible walls]] to prevent the player from exploring the wide expanse of Greenland surrounding the levels. Charging into them will cause Spyro to stumble back.
[[/folder]]

[[folder: First Person Shooters]]
* ''VideoGame/{{Borderlands}}'' has this in many areas. Falling off a cliff results in instant death, even though you can survive the fall most likely. Jakkob's Cove also kills your character if you try to jump off a cliff to get down to the docks as a shortcut, and going too far out in the water also kills you.
* ''Franchise/{{Halo}}'':
** Even though [[CutscenePowerToTheMax in various cutscenes]] you witness Master Chief surviving jumps and falls from ''the outer atmosphere''... fall 50 feet or so in-game and you're dead. Oddly enough, you die in mid-air rather than on landing. Even worse, many supposedly harmless drops are guarded by instant-kill barriers, usually to prevent players from shortcutting. Notoriously prevalent in ''VideoGame/{{Halo 2}}''. For example, on the Arbiter mission "The Oracle", even if you try to shortcut down the shaft by running around the narrow ledges, you will still be foiled by the death barrier (unless you get lucky and somehow avoid it). And then there are the water barriers, where MC suddenly acquires SuperDrowningSkills.
** Somewhat averted in Multiplayer in Halo 2, where super jumping (due to a patch gone right on xbox live) DOESN'T kill the player, even though they may fall in excess of 50 metres. Or how easy it is to get on the outside of the maps and fall off.
* ''VideoGame/HalfLife2'' has a rooftop chase sequence near the beginning. Even if the player manages to slow their descent, or jump down from ledge to ledge, if their feet touch the ground, they're instantly killed (as if from a fatal fall). The expansion ''Episode 2'' adds lush outdoor environments with mountain vistas and sprawling forests... but the player will often find his progress restrained by unclimbable cliffs that surround the valley Gordon Freeman stands in.
* ''VideoGame/Left4Dead'':
** The game has monsters appearing by climbing over barriers that players simply can't cross... or by leaping from open windows or rooftops that are unreachable from ground level. The implication is that more of the city would be reachable, if the players just had the right tools to climb it. Also, there are city streets visible from building rooftops, but these regions are unreachable because the only way to get to them would be a fatal fall. In the event that a player manages to survive a fall to the street below, but are not supposed to go there, they are incapacitated and then killed within one second. Gravity barriers also block the players from entering some of the monsters' [[RespawningEnemies spawn points]] -- infinite zombies "blink" into existence in an unseen, unreachable third-story room, then they jump out an open window to spill into the playing field.
** However, in "Versus" mode, the players take turns playing as the Special Infected, and they can explore these areas. There's not much to see, and the Infected-only areas are in turn blocked off by walls, sometimes of the invisible variety.
** On several maps in both games, gravity barriers are used as a point of no return. These are all very popular ambush spots in versus mode, as most can result in a guaranteed kill if the survivors aren't paying attention and fail to cross the barrier all at once.
* ''VideoGame/{{Marathon}}'' had numerous gravity barriers, where the player would fall off a ledge and be unable to backtrack. Since the game took place on a space station, these barriers only impeded movement because the artificial gravity was turned ''on''.
* Averted in ''VideoGame/SeriousSam The First Encounter'' with levels placed in the middle of vast, traversable deserts. Some such massive plains have secrets at the far end, if you deign to cross, usually not without a monster encounter mid journey.
* ''VideoGame/{{Portal2}}'' has these towards the end. Normally, Chell takes no damage from falling, since she's wearing the long-fall boots (Chell even falls over 4 km and survives at one point.) However, the last set of puzzles has a bunch of pits which kill you if you fall in them. Oddly, earlier puzzles had similar pits that killed you with a plausible explanation (there's toxic waste in the pits), but the pits in chapter 8 onwards are empty.
[[/folder]]

[[folder: Massively Multiplayer Online Games]]
* ''VideoGame/WorldOfWarcraft'':
** The game used mountains as gravity barriers when it was released. Unfortunately, they underestimated player ingenuity and it was possible to climb over most of them and reach empty lands with unfinished graphics. This was later fixed. It also uses water barriers, in the form of "fatigue" which quickly kills you when you're above sufficiently deep water, regardless of your situation (swimming, walking on water with magic, flying above the water, even as a ghost).
** You can try to fly from Northrend to Eastern Kingdoms only to discover that it doesn't exist there. The map says that the [=PC=] is over Eastern Kingdoms land, but it dies anyway.
** The expansion made gravity barriers temporary in the new content by adding flying mounts that could be obtained at high levels. This did not apply retroactively to old content, where flying is restricted because the landscape isn't designed for it. There is no HandWave.
** They're adding flying to the original maps in the new expansion. This time providing a HandWave: You have to purchase a "flight master's license" - presumably the same one that the griffon/etc handlers already have in order to sell you flights.
* ''VideoGame/{{Defiance}}'' has this, in the form of large hills. Initially, there is no way to scale the steeper ones, but with the right vehicle, enough booster, and a skilled player, you can scale nearly all of them. Unfortunately, that's when you will often run into the InvisibleWall if you're near a yellow line on your map.
[[/folder]]

[[folder:Miscellaneous Games]]
* In the ''VideoGame/{{Glider}}'' series, where VentPhysics substitutes for JumpPhysics, gravity barriers are usually just a matter of vents that don't rise quite high enough. Since helium in ''Glider PRO'' allows VideoGameFlight, outdoor areas have to use downward-blowing lift areas at the top to prevent players from flying out of bounds. Regarding the opposite direction, since falling speed is constant, narrow vertical passages can be protected by floor vents that need to be switched off.
[[/folder]]

[[folder:Platformers]]
* The ''SuperMarioBros'' and ''VideoGame/WarioLand'' platformers will often have secret items on high platforms unreachable unless the character comes back with the special feather, leaf, or other item that allows them to fly.
* ''Franchise/SlyCooper'' levels tend to be bounded by mountains and water.
* ''Franchise/SonicTheHedgehog'':
** ''VideoGame/SonicTheHedgehog1'' had gravity barriers. There is a hill in the Marble Zone (part one) that you can run down but cannot run back up. It also had others that you could only go back up very slowly. So, gravity-impatience barriers. Now, the latest ''Franchise/SonicTheHedgehog'' games have entire levels SURROUNDED by these, which, due to the inexplicable insistence on extremely linear paths, winds up with long stretches of road over BottomlessPits. This hasn't been met with much applause.
** Occasionally used in ''VideoGame/SonicAdventure2'', usually on the treasure hunting stages. Mad Space and Meteor Herd have these surrounding the level, forcing the player to turn back should they stray too far from the path. Barriers are also used in Chao World, preventing Chao and the player from stumbling off the cliff edge.
[[/folder]]

[[folder: Racing Games]]
* Averted by virtue of sheer incompetence in ''VideoGame/BigRigsOverTheRoadRacing'' where it's entirely possible to drive right over the cliffs surrounding the track and head into the infinite grey void.
* Some racing games (typically of the 'kart'-style) have these as part of the atmosphere, but it also does prevent turning around and driving back. And then there's the ones where the cliff version of the barrier is in effect, where if you leave the track you really leave the track; in ''VideoGame/MarioKart Wii'', do this on Rainbow Road and you get to watch yourself do a re-entry burn.
* On that note, the ''JetMoto'' games for the Playstation would often prevent backtracking with huge one-way jumps and large drops off unscalable cliffs. And, of course, half of each game's tracks were loaded with {{Bottomless Pit}}s.
* ''VideoGame/MotocrossMadness'' had a GravityBarrier that can actually be scaled, allowing you to face the ''second'' safeguard: the [[InvisibleWall Invisible Cannon]].
[[/folder]]

[[folder: Role Playing Games]]
* ''Franchise/TheElderScrolls'':
** The developers of ''VideoGame/TheElderScrollsIVOblivion'' ''attempted'' this: the many mountains surrounding the land were (mostly) intended to be insurmountable (there are even a few glitched areas that are covered by a perfectly flat ground). Just in case the player does make it to the end of the line, the game pops in with an InvisibleWall for good measure.
** Several player-created mods remove the invisible walls and make whole provinces like Elsweyr and part of Morrowind reachable, with player-made but roughly in-canon places to visit.
** ''[[VideoGame/TheElderScrollsIIIMorrowind Morrowind]]'' likewise attempted this by bracketing many paths with tall hills you couldn't climb. But apparently the guy who designed the terrain never consulted the guy who wrote the Levitation spell or vice-versa.
** ''[[VideoGame/TheElderScrollsVSkyrim Skyrim]]'' makes it [[RuleOfThree a hat trick]]. The super-tall mountains can be scaled fairly easily with a [[AutomatonHorse horse]], leading to the [[http://i.imgur.com/Xaoka.jpg "Physics? B****, I'm a horse"]] {{meme|ticMutation}}.
* ''VideoGame/{{Fallout 3}}'' uses this on most of the edges of its large map -- nuclear war seems to have kicked up box-shaped range of mountains around Washington DC. If one tries to swim off the south edge through the Potomac, or walk to an unblocked map edge elsewhere, however, you are simply stopped by a pop-up telling you [[InvisibleWall you can't go any further]]. ''VideoGame/FalloutNewVegas'' prefers to block the gaps in the surrounding hills with insurmountable waist-height obstacles such as wrecked vehicles. Both games also have a few barriers of the lethal variety, where falling off a precipice results in mid-air death and a FadeToBlack as if it were a BottomlessPit. Most notable in the ''Lonesome Road'' DLC.
* ''VideoGame/{{Xenoblade}}'' has these around many of its [[SceneryPorn incredibly huge and detailed environments]], where the characters will fall to their doom if they cross them. Justified, as most of the game takes place across the bodies of two continent-sized giants.
[[/folder]]

[[folder: Survival Horror]]
* ''VideoGame/AlanWake'' does this, being set in the mountains of Washington State. There are plenty of areas where gravity barriers stop you from travelling off the beaten path, and yet it works really well. Good level design, thy name is Alan Wake....
* This is what traps victims in the town of Franchise/SilentHill. More specifically, the colossal, bottomless chasms that spontaneously appear and turn the town into a mist-shrouded plateau. And you can fall into the BottomlessPits in later games. Though this one [[FridgeBrilliance actually makes a lot of sense]]. Since Silent Hill is a malevolent, [[GeniusLoci probably-sentient]] EldritchLocation, of ''course'' it'd go out of its way to trap people inside.
* In ''VideoGame/SurvivorTheLivingDead'', you can't drop from the second floor to the ground as 'Jumping off will snap my skinny legs for sure'. You ''can'' throw bombs from the balcony, however, though there was a glitch in some versions that caused them to ''bounce back up''.
[[/folder]]

[[folder:Third Person Shooter]]
* ''VideoGame/{{Crackdown}}'''s Pacific City is surrounded by water. Swim too far away from the city -- a good distance, surprisingly -- and you'll run across an invisible wall.
* ''VideoGame/RedDeadRedemption'' has insurmountable cliffs surrounding the map.
* The ''VideoGame/SyphonFilter'' series is somewhat inconsistent with these, a fall height that may be harmless in one situation or game will be fatal in another.
[[/folder]]

[[folder: Wide Open Sandboxes]]
* The town in the first three ''VideoGame/AnimalCrossing'' games has huge cliffs to the west and east of the [[LawOfCartographicalElegance square town]]. The second and third games also has a cliff at the north, where the first has a fence. In addition, the first and third games have cliffs across the middle of the town that (along with the river) separate the town into four quadrants. In the fourth game, your town has a cliff to one side and a path leading to the commercial district on the north side, with the other two sides being bordered by ocean.
* All the ''VideoGame/GrandTheftAuto'' games have water barriers.
** ''San Andreas'' is an exception since there are no barriers to physically hold your character back, although the longer you go away from the mainland, it will take just as long to go back - and realistically, if you just swim off the coast trying to reach the edge you'll run out of energy before long and drown (no such problem with planes, though). And if you go into other towns when you are not allowed yet, you get an unshakeable wanted rating, justified by the plot.
* Subverted in ''{{Minecraft}}'': sheer face cliffs exist that are impossible to traverse...that is, until you mine some steps in them, or use a water bucket to make an impromptu elevator out of a waterfall.
** Beyond X/Z 32,000,000 meters, the blocks cease to be solid, so traveling here will cause you to fall into the Void.
* ''VideoGame/MystIV'' has a one age with sheer cliffs. ''VideoGame/MystVEndOfAges'' also has some.
[[/folder]]

!!Non video game examples

[[AC:Tabletop games]]
* ''{{Ironclaw}}'' included a GravityBarrier in a TabletopRPG. In the middle of the map are the Walls of Calabria: a v-shaped cliff formation leagues long and a mile and a half high. Of course, they're not as much of an obstacle for the flying races, and the second edition reveals that a Noble House of Bats claim the caves riddling it as their domain.
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