Sliding Scale of Video Game World Size and Scale
Some video games attempt to portray a realistic, convincingly-sized world for players to explore and experience. At the same time, the gameplay experience is still the most important thing, as games that are intimidatingly large could also end up not fun to play, not to mention from a technical standpoint, a big game world can be taxing on a game's resources. So game companies trying to balance believability with fun try different techniques to make a convincing world.
There's many ways to do this, each with their pros and cons. Done wrong, the world can be unconvincing, or the player might be intimidated by the sheer size and scope of it all. Done right, the game is both fun to play and immersive. Here are the major techniques game companies tend to use to try to make their worlds feel believable without sacrificing gameplay.
Real-time, small scale world
Many video games, striving for maximum interactivity, allow players to go to any part of the world in real-time, allowing them to explore everywhere and trying to give the feeling that the world is a real, livable place. However, because the world must be scaled to be convenient for gameplay, this can result in the world feeling very small, since each individual area must be small enough for players to explore and go everywhere, and they have to be able to easily travel from place to place in real-time. This results in, for instance, towns with maybe 20 townspeople and 10 houses and 1 store, for instance, and other areas that might look like real places but only so long as you don't roam through them and see how small they really are. This can be a believability problem for story-driven games.
Visit parts of map
A less common method is to have a map and let players visit segments of it, implying that the world itself is in fact massive, but players are only exploring the story-important chunks of it. The individual areas may or may not have a realistic scale (they often tend not to), but the map itself lets you click on the area you want to warp to next, while showing a bigger world than you can actually visit, with the visitable areas being the only ones selectable. It essentially says that the world is big, but you're visiting only part of it. Most common in action games.
Many RPGs go for a very specific method of making their game world feel large. When you're in a town, things are to scale (and the result is that the towns themselves tend to feel small), but when you're outdoors, you're generally on an overworld map, in which things are not at all to scale and everything is made smaller, to give the feeling that you're traversing a large map. The map itself may not be physically large, but because it's a clear symbolic representation of a large world, the world can still feel big.
Realistic scale, most of world in background
This is a technique many modern games use. Buildings are as big as they are in real life, cities are, and so on, but you the player are limited to a specific path and you cannot explore the world outside that path, but you can certainly see it. Buildings, mountains, etc. are often in the distance, but you can't ever reach them, as they're there just to make the world feel huge. The distance you physically travel to get from place to place is also realistic within the limited scope you can visit of the world. This approach is favored by Uncharted, which lets you explore limited parts of jungles, towns, caves, and so on, but has the places you can't reach visible in the background to make them feel believably large. This style tends to be used mostly in linear games, as it would be rather questionable in an open-world game.
Realistic scale, locked doors everywhere
There's also making a large world but locking most of the doors or simply not allowing players to enter most of the buildings. So you travel the distance it should realistically take to go from one side of a large town to another, but because you can't enter most buildings, the company is spared the problem of having to design their interiors. Plot/gameplay-important buildings are likely to be somehow marked, or otherwise made obvious. Some games - notably, the Silent Hill series - go for a somewhat different approach, in which players can explore realistically-sized buildings but most doors are locked.
Realistic scale, tons of buildings enterable
Very very rare for one simple reason: It's extremely difficult and time-consuming to make! It also can result in a world so massive and open that players can feel intimidated. The Elder Scrolls games are known for this, particularly the second game, but later games decreased the size and scale of the world while still keeping it massive by video game standards. Making such a game often requires recycling assets - for example, creating a handful of houses (interior and exterior alike) and reusing them. Any game with an enormous scale does this out of necessity.
Now bear in mind that there are hybrids of these approaches in existence, so these 6 styles are only general rules and not the only way to create the illusion of a convincing world.
For example, the NES game based on the movie Who Framed Roger Rabbit? allows you to explore a city that's very large for the standards of the time, and nearly every single building can be entered. However, with the exception of certain unique buildings, the interiors of the buildings are nearly identical and recycled. There's also a second town that can be visited, and the two are separated by a tunnel that warps you from one location to the other. This is a mixture of Realistic scale, tons of buildings enterable (because every single building can be entered) and Real-time, small scale world (because the world is smaller than equivalent real life locations would be).
- The Legend of Zelda series does this all the time. Towns are small and might have only a dozen buildings, if that. Forests, fields, mountains and so on are all small compared to what they would be in real life. Because all travel is in real-time, rather than the world being symbolically represented, the result is that it can feel rather small, and not like a world anyone could actually live in. Even as a single country, it's small.
- While World of Warcraft, with its 2 "planets" (as they're represented as such on the map), 3 continents on the main planet, and numerous regions per continent is absolutely enormous by video game standards, it still technically belongs in this category. Each region is quite small by real life standards and can be flown over in the span of a couple minutes. Furthermore, the regions are so condensed that major landmarks are within only a few miles of each other, sometimes with two or more visible when flying overhead. The world, while large, is more about density (things you can do in each area) than total size.
- The various Grand Theft Auto games would under a form of real-time, small scale world (for example you can drive across San Andreas in a couple of minutes, even though it's meant to represent a whole state). However, the games also usually feature the locked doors everywhere feature, in that there's usually tons of buildings but few, if any, are actually enterable.
- Driving times ARE shortened by the fact that you're normally driving pedal-to-the-metal without a care about crashing. But even if you did drive like people do IRL, the locations are still much smaller than their real-world inspiration.
- The world of An Untitled Story has almost all of its areas directly connected to each other with next to no transition. MountSide and BlackCastle are an exception, as the only way to reach them is through teleporters (if one has to believe the map, one is located under DeepDive, while the latter is buried under LongBeach).
- Red Dead Redemption has a very large world that takes a long time to travel through by horse or train, with many towns, and locations in both Texas and Mexico. However, it's definitely not to scale, and while large, it's much smaller than real life for the sake of gameplay, thus fitting easily into this section. (For comparison's sake, the map is the same size as Grand Theft Auto IV but feels larger because there is no city to occupy the space, and you can't drive.)
- The Ship takes place on cruise ships. While some are larger than others, all of them are smaller than real-life cruise ships. The largest one has 7 decks; in real life, 12 decks is an average height. More than that, they aren't as large overall (width/length) as real cruise ships, and there are liberties taken with the layout (for example, not every deck has bathrooms!).
- The Harvest Moon series uses small towns, with every part and building of the town being accessible. Usually, this means an overworld with about 20 enter-able buildings, with some being houses, some being shops, and some of them being combinations. The overworld also generally has one or two medium-sized "wilderness" areas to roam in.
- Almost every inch of the planet's dry land is accessible in Albion. Many buildings can be entered and they are all unique. On the other hand, the overall size of all settlements is incredibly small, and despite still being incredibly vast (with not too many features of interest), even the largest continent in the came can be crossed in the course of a single day on foot, and the entire world's population is barely a three digit number. This is handwaved by people stating that the planet is very small, and the almost earth-like gravity is due to the high density metal underground (also explaining why time goes by so fast), and by narration accompanying sea voyages as lasting for several weeks, implying that most of the surface is water. Still doesn't explain the small population.
- Dragon Age uses this. You can often also see mountains and buildings stretching into the distance to make each area feel large, but the map lets you warp between them. To give the feeling of genuine travel from place to place, a trail is drawn on the map leading from the current area to the next, and the trail is always drawn at the same speed regardless of distance, letting farther away places feel farther away. There's also a city that is so large it's divided into multiple sections that are visited separately via map, giving it the feeling of being realistically large while still limiting the player only to the important areas.
- The early 1980s game Agent USA has you traversing the entire contiguous United States. There's a map showing only the major cities of each state (which means hundreds of cities), but they are reachable only by train. The length of the train ride (with sped-up clock) is determined entirely by the distance between cities, so if the distance between two cities is three times the distance between a different set of cities, the ride will take three times as long, to simulate the feeling of distance scale.
- Half-Life 2 uses this to make City 17 look like a real city, but most of it is blocked off by rubble or other things (including tons of locked doors) preventing you from exploring. The rest of the world also stretches farther into the distance than you can visit.
- Other Valve games, such as Left 4 Dead, do the same.
- An approach favored by Uncharted. Cities can have literally hundreds of buildings stretching into the distance, but you're unable to go near them, being limited to the ones important to gameplay.
- For the most part, Halo has very large levels with even larger, expansive background areas that are usually blocked off by cliffs/drop-offs.
- Call of Duty games fall under this as well. Buildings and streets are realistically rendered, and often the player can easily see detailed background elements. However, rubble or random props will block certain pathways, ensuring the player can only take a linear path through the level.
- Deadly Premonition takes both the "world is big but most buildings can't be entered" and the "buildings are big but most doors can't be entered" approaches. The game takes place in a realistically-sized "small" rural town that would be a small town by real life standards, but is large by video game standards considering how much there is to explore.
- Silent Hill has many realistically-sized environments that you mostly travel to entirely in real-time rather than reaching them via cutscene, and uses the "locked doors" approach.
- Games like Microsoft Flight Simulator (playable area is the entire Earth) or Orbiter (entire Solar System). Since you can't go indoors and explore interiors as well, they technically fit this category.
- The Spiderman 2 game for Gamecube, PlayStation 2 and Xbox recreated the entire scale of Manhattan! On the other hand, most buildings couldn't be entered, and the few that could didn't let you explore much inside.
- City of Heroes/City of Villains: Except for a few "special" locations (like AE, City Hall, the police stations and the hospitals) building doors could not be entered at will. With the release of Going Rogue and the redesign of Atlas Park, there came another exception -- "staircase" doors that would take you immediately between ground level and the roof (or top floor) of a building. But beyond that, every door was locked. If a structure had an interior that you could enter when not on a mission, it almost never had a door, just an entrance you could walk through. (For example, the underground Council base in the Rikti War Zone.)
- The earliest Elder Scrolls took this to an extreme. While later ones still technically do this, although they dial it down a bit. Skyrim, for example, has a smaller, more intimate world than previous games in the series, with towns that have only a dozen or so buildings, and a walking distance between locations that takes ~10 minutes to go from one to another, making it more an example of real-time, small scale world. However, there's still a large amount of ground to cover, a great many cities, towns and outposts, and every single building can be entered. The world is very large, but definitely nowhere near to scale.
- Opoona has several absolutely massive cities, with truly enormous explorable areas. In addition to huge "business" areas, the apartment areas are also elaborately crafted in such a way that they resemble real apartments—everyone finally has their own bathroom! The overworld areas even seem a bit small in comparison, though they're still quite large. And although the first few areas have to be traveled between in flight (the "parts of the map" variant), the later areas get interconnected such that it takes quite a bit of time to traverse them.