Chokepoint Geography

"The only way to travel by land between different areas of a continent will always be through a single narrow pass in a range of otherwise impenetrable mountains. Usually a palace or monastery will have been constructed in the pass, entirely filling it, so that all intracontinental traffic is apparently required to abandon their vehicles and go on foot up stairs and through the barracks, library and throne room to get to the other side. This may explain why most people just stay home. (In some cases a cave or underground tunnel may be substituted for the palace or monastery, but it will still be just as inconvenient with the added bonuses of cave-ins and nonsensical elevator puzzles.)"

- The Grand List of Console RPG Cliches #67

The hero's journey is a long, winding road, fraught with dangerous monster battles, maybe a princess to save, and the inevitable dungeon. Many game designers (mainly console RPGs) have a story to tell, which involves you and your party going from Town A to Dungeon B to see NPC C, and occasionally going back to Town A to stock up on supplies for the next encounter.

With that principle in mind, the world map will be designed in such a way that one or more dungeons will lead to parts inaccessible by travel on foot. You may have to bypass a Beef Gate at the end by defeating it in a Boss Battle, at which point you can travel freely through the dungeon at your leisure (provided you can still handle the monsters that lurk within). The Bonus Dungeon is almost always exempt from this trope, since those are often placed in far out-of-reach locations, presumably to dissuade newbie adventurers from getting themselves killed after wiping their feet on the welcome mat.

Compare Convenient Questing and Insurmountable Waist Height Fence. Can be circumvented completely once you Get On the Boat or acquire a Global Airship.

Real Life

 * Truth in Television, especially before the invention of air travel and still relevant in the maritime business.
 * The Straits of Hormuz, which separate the Indian Ocean from the Persian Gulf (with major oil fields) are a case in point- sink a couple of vessels in there and you seriously damage the global economy.
 * The Suez Canal was blocked for several years following the Six Day War of 1967.
 * For a more recent example that hits nerds closer to home, an accident in the Suez Canal in 2004 blocked a shipment of Playstation 2's heading for the UK holiday season.
 * Thermopylae, anyone?

Video Games

 * A variation occurs in many Real Time Strategy games, where the map is often a square shape and units cannot exit the map to circle around. Similarly, forests (or other large swathes of resources), rather than being treated as rough terrain, are often obstacles...as long as they're still standing. This can lead to interesting moments when a less-experienced player will set up his base to defend via chokepoints created by trees...only to be rather screwed later in the mission when his worker units have removed all the chokepoints.
 * This trope occasionally pops up in Turn Based Strategy games, most notoriously the Advance Wars series, where a one-tile pass can be completely choked off by placing a fighter jet on the open tile. If the enemy force has no units which can attack a fighter, you've effectively created an inassailable buttplug that breaks the map in your favor.
 * In order to not break the game's sequence, in Baldurs Gate II you start in Waukeen's Promenade and have to go to the Slums next, where you meet a representative of the Shadow Thieves who offers to help you and gives you a goal to shoot for this chapter. From the Slums, no matter which way you exit, you can suddenly go anywhere in the city.
 * Brutally subverted in Perfect World. Usually, the only thing leading you to your next destinatination is a small path and a yellow arrow. This has led to certain new players ending up in places inhabited by level 50 or higher enemies.
 * It's even worse with the Winged Elf race. This race has wings, so now all that's guiding you is a yellow arrow if you decide to fly there. Granted, all characters get flight at level 30, so everyone has this problem.
 * A new(ish) patch allows you to set an icon on your map that signals where you have to go (provided you check your quest log frequently), complete with an auto-walk/fly feature that makes a beeline to it; however, if you're not flying or paying attention you can easily fall down mountains, run right into walls or end up in higher level areas.
 * In Diablo II, the only way out of Khanduras (Act I) to the Desert of Aranoch (Act II) is through the Rogue's Pass, a narrow monastery pass through the mountains defended previously by the Sisters of the Sightless Eye and presently by the hordes of hell.
 * Instead of having to go all the way through the monastery, there is a set of portculli that wagon caravans like Warriv's presumably take. The REAL mystery is how they got through The Underground Passage, a network of narrow, twisting caves just before the monastery.
 * Dragon Quest I utilized this with the swamp cave leading to the town of Rimuldar, the first of only a few places in Alefgard where you can purchase Magic Keys.
 * Dragon Quest IV: The Final Boss is in the Overworld behind the Final Dungeon, since you can only take your active party into a dungeon. This way, you can use a magical horn to summon the wagon with your inactive party members, who can then swap in and out during the big showdown. You remembered to give the horn to one of your active party members, right?
 * Final Fantasy IX: Conde Petie, the dwarf home situated on two roots of the Iifa tree spanning a chasm between a large plateau and the mountains, blocks passage to the Iifa Tree and Madain Sari, the village of the summoners. Note that the various Gates (South Gate, etc.) are not examples of this since, while they regulate passage through the mountains, they do not involve stairs or narrow areas that would prevent vehicular transportation.
 * Gizamaluke's Grotto on the other hand, would.
 * In Final Fantasy VIII, your trip to Galbadia Garden takes you through a forest in a narrow mountain pass. As soon as you set foot in that forest, the second Laguna sequence in the game begins, forcing what is effectively your party into a weird crystalline dungeon.
 * In Legend of Legaia, several such blockades exist: Drake Castle (blocking Drake Kingdom from Mt. Rikuroa and  cave; bypass-able ), Mt. Rikuroa (blocking Drake Kingdom from   cave; bypass-able  ), the Biron Monastery (blocking Drake Kingdom from the East and West Voz Forests   and the Ancient Wind Cave), the Ancient Wind Cave (blocking Drake Kingdom from the Sebucus Islands;  explains that there haven't been travelers since the mist came, so travel between Drake and the Sebecus Islands before then presumably had to travel through the narrow caverns and consisted only of people on foot or ), and . The Sebucus Islands go on to prove this game is filled with the cliche. Almost all of these literally follow the Mountain Passage premise, and those that do not operate in a similar fashion. Biron Monastery is a near-perfect example in that you must enter through narrow doors (multiple sets), proceed through the training/entrance hall, through a shrine room (close enough to a throne room), up stairs, past the sleeping quarters (barracks), and through another hall and up the stairs in the hall (multiple sets) and then out two more sets of narrow doors.
 * The Biron Monastery gets a pass, because the deadly mist that's been covering the world for the last ten years had to be held back somehow, and the solution to that was to make all entrances and exits in Biron airlocks. Traffic is restricted, but since there's no traffic to speak off, it's not a problem.
 * The Lufia series uses this trope a lot. Caves feature stairs leading out (or in, depending on your perspective, but you only see the stairs once you're inside), and many caves are mandatory routes of travel from one place to another (without a ship or submarine), which would seem to make traveling with a wagon or any sort of vehicle difficult. Also, many of these caves appear to be dark and wet and leading horses or any wheeled vehicle down a slippery set of stairs in darkness is not conducive to safe travel (though there are monsters anyway, but a sword can't thwart the danger of slipping and breaking your leg). The argument could be made that the stairs are simply an abstraction, but they could have just as easily abstracted a gradual slope rather than clearly cut (and bumpy for wheeled travel) stone stairs.
 * The first Star Ocean featured the city of Coule sitting right smack in the middle of a mountain blocking travel between Kraat and Portmith.
 * Star Tropics. Several times. This game perfected the implementation of the Fetch Quest, But Thou Must, and Broken Bridge tropes.
 * Golden Sun has this; in fact, one the few occasions were it doesn't have it, it's common for players to miss the town/dungeon that they were meant to go to first (for example, people attempting to go to Kolima and instead going north and fighting Saturos - who is a very hard early-game boss with 2000HP - and then fighting the first real boss, Tret - who has 500HP).
 * Especially annoying in Phantasy Star III, even if you're a Layan. Throughout the earlier generations, the only way to get to other worlds is by traveling through caves.
 * This is justified in Morrowind: The Elder Scrolls. The only way into the Blight is through an inn/barracks/base filled with soldiers. It makes sense, because it's stopping the blight getting out.
 * However, you can freely hover over the wall at any point if you have a levitate spell, which can be learned very early in the game. Elder scrolls games generally avert this trope, you can generally travel freely over the game's area without any restrictions.
 * Plus you don't actually have to go inside the building, you just have to hit a couple of buttons to open the gate.
 * World of Warcraft has this in Azeroth, where different areas are usually connected only at specific points, with the rest of the border blocked by impassable mountains. Averted in Outland and Northrend when you get a flying mount, when you can fly anywhere you like.
 * For Cataclysm, Azeroth has been redesigned for full freedom, too.
 * Ossa Trail and Gaoracchia Forest in Tales of Symphonia.
 * In Tales of Vesperia, you have to go through a cave called the Weasand of Cados to get to the desert from Nordopolica.
 * The Legend of Dragoon is made of this, especially on Serdio. To get to Hellena Prison from Seles, you have to go through the Forest. From Hellena to Bale, you have to pass through the Prairie and Limestone Cave. From the Kingdom of Basil to the Sandoran Empire, you have to go through the Volcano Villude and the Dragon's Nest. Disc 2 is just as bad in Tiberoa.
 * In Wandering Hamster, Bob and James have to pass through the Troll Mountains to get to Lord Broaste's castle the rest of the world.
 * The map of Shining the Holy Ark is split down the middle by a mountain range. The only way to get through is by a going through a series of caves, that are of course invested with monsters. The top of the map is covered with Frictionless Ice which seemed to be designed to waste the players time.