Sliding Scale of Linearity vs. Openness

Some Video Games are linear, forcing you to follow one set path throughout the whole game. Other games are more open, allowing you to choose how you progress to your goal. Some games are are even more open than that, giving you a wide open world to explore at your leisure. Most Action/Adventure/Action Adventure/Platform games fall somewhere in this spectrum of linearity and openness; this scale exists to catalog exactly where they fall.

The Sliding Scale of Linearity vs. Openness is comprised of six categories for ranking how linear or open a game is. The lower on the scale a game is, the more No Sidepaths, No Exploration, No Freedom it is; the higher on the scale a game is, the more Wide Open Sandbox it is. Platform Games will usually rank low on the scale (by design), while Role-Playing Games will usually rank high on the scale (by convention).

The most important factor in determining where a game lies on this scale is the game world itself. A game that limits you to one path will rank lower on the scale than a game that presents an open world and lets you decide how you are going to get to your objective. The objectives themselves are also important in determining a game's place on the scale. A game with a set story progression and one goal or a linear series of goals that get you from the beginning to the end will rank lower than a game with many Side Quests or a game with multiple ways to progress through the main story. A game can still rank relatively high on the scale with few side quests if it presents you with many missions that are required to complete the main story line and lets you decide how/in what order you will accomplish them. The way the story is set up, however, will usually be influenced by how linear or open the game is, not the other way around.

Levels:


 * 1) The game follows a linear narrative, as well as a largely linear pattern with how you move between levels and/or within the levels themselves. Any attempts at exploration will be inconsequential if not outright fruitless. There might be secret warps to later stages, but any bonus stages will be entered automatically. Rail Shooters are this level taken to the most extreme. Auto Scrolling Levels may be present. Games that fall into this category have become more and more rare with the passage of time. Majority of cinematic shooters fall into this category though.
 * 2) Though games at this level will still be largely linear in their design, you will have some choice in how you progress. You may be given a choice between two paths that take to you to the end of the level, or you may find a bonus level on the side that gives some reward before plopping you back on the main progression path. Exploration may result in some interesting discoveries. Many old-school first-person shooters fall into this category.
 * 3) Overall progression becomes less linear at this level. While levels themselves will still have a "get from point A to point B" feel, you will have many options in how you get from point A to point B. Backtracking will now be allowed, even if only to allow you to replay levels that you liked; whether the levels change from your initial trip through will vary from game to game. There is still a central narrative, of course, and these games are still on the more linear side of things, but they will not be constrictingly linear. Side Quests may be present, but will not feature prominently.
 * 4) We now get to the more Metroidvania type of games. These games will likely allow you to explore and do side quests, but they will still want you to put the storyline first. Exploration will be encouraged, but controlled, with more of the game world opening up to you as you play. Games at this level will frequently play out such that you won't be able to explore the world or deviate from the main storyline at all in the beginning, but the whole world will be open to you by the end. Games can also fall into this level if the whole world is open to you from early on, but there's little reason to explore it other than to see the sights, and thus the main storyline will still be your primary concern.
 * 5) Open-world Role-Playing Games. Games at this level will have plenty Side Quests and a very open world. (Some will still open up more of the world as you progress along the main storyline, but from the beginning, you will feel like you have a wide world to explore.) The main storyline may still be emphasized over the side quests, but it's not unheard of for games at this level to emphasize both equally. The central narrative itself may branch off into multiple paths, usually accompanied by Multiple Endings.
 * 6) Wide Open Sandbox games will be very de-emphasized and, if there even is a main storyline or central goal, it'll likely only comprise a very small part of the whole experience. You are free to do whatever you want in these games, and those at the highest end of the spectrum will have no limits on what you can do. There may be a plethora of Side Quests to keep you busy, or you may just need to make your own fun. Most MMORPG games fall into this category. Beware of sinking into the Quicksand Box.

See also the Sliding Scale of Content Density vs. Width.

Level 1

 * Most railshooters, although some provide branching paths that make them level two instead.
 * House of the Dead
 * Paperboy. You go from start to finish.
 * Rez
 * Many side-scrolling platform games.
 * Radiant Silvergun, except in arcade version where it is level 2.
 * Wonderboy / Adventure Island 1: You go from left to right and there's no exploration except an occasional bonus stage.
 * Tank Force. Enemies appear, kill enemies, repeat 35 more times, victory.
 * Toki, a platformer taking place linearly in 6 stages.
 * Bit.Trip RUNNER where you move right and only jump, slide and block and kick on certain intervals.
 * Though the style of gameplay in the Battletoads games tends to vary from level to level, the linearity in level design is very consistent.
 * Cryostasis. The game follows a linear narrative and usually only a single path is available to take.
 * Battlefield 3 single player campaign where the levels are getting from point A to B while regularly stopping to fight or have a cutscene.
 * Home Front single player. You are hand-held throughout the entire game and have to do what must be done.
 * Modern Warfare series single player campaigns also go to category 1 as there are are numerous setpieces and to make the game feel more dramatic, like a movie.

Level 2

 * Final Fantasy XIII, whose linearity created a huge amount of controversy, not only about whether it was good or bad but whether it was true to the series.
 * Final Fantasy III, Final Fantasy IV and 'Video Game/'Final Fantasy X'' probably also go here. You can revisit old areas, but there's little reason to.
 * III and IV, at least, are arguably more 3s - they have a decent number of sidequests, though they're linear in the long run.
 * God of War
 * Halo
 * Resident Evil 4
 * The original Super Mario Bros just barely made it to this level with its hidden bonus areas. Super Mario Bros 3 almost exceeds it.
 * Half-Life (justified in-story from the second game onwards as behind-the-scenes manipulation)
 * By the same studio, Portal, insofar as many of the puzzles have multiple solutions and the player is often free to muck about for awhile.
 * Visual Novels, if you consider them games, don't normally have more than different narratives depending on your selection. Some are level 1, though.
 * Ace Attorney
 * Doom. You're supposed to collect keys and get to the exit, but there are also quite a few side areas which you can explore to find items, enemies to fight, or just out of curiosity what's there. Also, sometimes you have two or more ways of getting to the exit, and generally you can freely backtrack to early areas of the level. Custom maps often are less linear, sometimes qualifying as a 3.
 * Glider PRO houses, on average. Bonus rooms and branching paths are common, but backtracking is often unrewarding or impossible. The mechanics of the game don't really allow for side quests.
 * The Genesis and later modern Sonic the Hedgehog games which have multiple paths to complete the level, although the level layout is still linear.
 * Flower. You go from point A to B, but you'll likely explore on your way.
 * Eversion also falls to this category. It's rather linear, but levels often require lots of backtracking.
 * Serious Sam series. Layout is usually very linear, but there are secrets to discover. Serious Sam II has the most linear paths, 3 has the least of them.
 * Eternal Sonata: most attempts at exploration are thwarted by the characters.
 * Bug!!. There is only one end to a level, however, there is usually more than one path that Bug could take to get there. Bonus levels are also scattered around the area too.
 * Far Cry. There are often many ways to tackle the level with a lot of paths to the goals.
 * Soldier of Fortune series.
 * ''Journey. Although it follows a linear narrative, the areas are often very large and exploration is often encouraged and rewarded.

Level 3

 * Cave Story feels like a Metroidvania game, but is more linear than usual. The progression through the levels is limited by the plot and many levels are linear in design, but backtracking is rarely difficult and there are a bunch of rewarding side quests.
 * Most Final Fantasy games. You have a handful of sidequests and might be able to visit a few places early, but it's all about the story. Though their non-linear last acts tend to be closer to level 4.
 * Iji, where each level is a miniature Metroidvania.
 * The Metal Gear Solid series, though close to a 2, makes it into this level. There aren't any side quests (at least, not in 1, 2, or 3), but exploring can lead to weapons, ammo, and supplies that can make your experience easier, and there are plenty of ways to navigate each room/area.
 * In 3 there are what you might call sidequests in the form of destroying weapon and food supplies, also a few things like destroying the helicopter or killing The End early on.
 * Sonic Adventure 2 (though the Chao raising minigame is decidedly level 6)
 * Spyro the Dragon
 * Super Mario World is still mostly linear, but does offer some options as to the routes you take. Many levels have two different exits which set you off on different paths along the map. Though all the road splits either eventually meet up again or lead to the bonus areas, you do have some choices how you progress through the map if you're not trying to find everything to get 100% Completion.
 * The Tomb Raider series in general; levels throughout the series might only have one exit, but are frequently quite open beyond that. Some of the games are arguably closer to level 2 however; and others verge on Level 4.
 * The MOTHER series
 * Adventure Island IV. There are plenty of side routes although most of the level layout itself goes fairly linearly.
 * Metroid: Other M (although edging towards a 2).
 * In Blaster Master series, levels are opened in order, but there is a lot of backtracking to do and plenty of side areas.

Level 4

 * Assassin's Creed
 * The Banjo-Kazooie series
 * Deus Ex: The "acts" are self-contained, and until you complete the task you can't advance to the next area, but within those acts you can explore and use stealth, hacking or shoot-em-up to complete your tasks. However, many of the more linear sections (especially later in the game) come closer to level 3.
 * Dragon Age: You're locked into your beginning (one of six), the main storyline is always the most crucial thing, and while you can explore side quests concurrently with the main plot, certain areas of the game remain locked until certain points of the main story (often with a Beef Gate).
 * Final Fantasy V. Lots of sidequests and exploration, solid main plot.
 * Final Fantasy XII, verging on Level 5. There's probably more gameplay in the optional material than the main story, but you don't have to do any of it.
 * The Harvest Moon series
 * The Metroid series (with the exception of Metroid Fusion, which is more of a three) and the Metroid Prime series (though Metroid Prime 3 was also more of a three)
 * No More Heroes has a wide open world, but there is little reason to explore it.
 * Tales of Symphonia
 * Skies of Arcadia
 * The 3D Super Mario games. Super Mario Galaxy is a level 4 in terms of overall structure but most levels are Level 2, while Super Mario Sunshine and Super Mario 64 remain 4's throughout (and verge on 5 when enough of the game is opened up).
 * Batman: Arkham Asylum. You work your way through a single linear storyline with only one sidequest (solving the 240 Riddler riddles, which is a borderline example of a sidequest) but you are free to travel anywhere on the island and use newer gadgets in older levels to discover new secrets. The actual story takes you back through at least four previously explored locations. A Metroidvania title.
 * Borderlands.
 * Seiklus. There is a main objective but you can start doing this from any end. There are few sidequests though.
 * Chrono Trigger and Chrono Cross feature (multiple) worlds that you can easily explore and open up fairly quickly, with numerous optional sidequests and incentives to revisit old areas. In Chrono Trigger, you can fight the final boss at any time starting less than halfway through the game; in Chrono Cross, you can make numerous important decisions that affect which areas you will need to navigate, which characters join your party, and how various subplots are resolved. Both games feature Multiple Endings, though without using New Game Plus, they are implausible in Trigger and impossible in Cross.
 * That's actually a minor overstatement, though: There's three ways to get to the boss fight in the end game. The Black Omen and bucket endings are very similar, but crashing your time machine into the boss gives a unique ending, albeit a rather unrewarding. There's also a unique BAD ending you get by losing to Lavos. All of these are readily available first playthrough, but there's far, far more variation in the more difficult endings, most of which - if you can get them at all in the first playthrough - need ridiculous amounts of level grinding. There's also a lot of endings only available in New Game Plus, because that adds some additional time travel gates.
 * Most Zelda games fall into this level. Though the original game and Majora's Mask are Level 5, and A Link to the Past turns into level 5 after the first dungeon of the Dark World.
 * 1000 Amps. Eventually you'll get to the main branching hub and you'll start to can start beating each branch of the world from there.

Level 5

 * Arm A II. The majority of battles are not scripted, player needs to decide where to go and how to approach objectives etc.
 * The Grand Theft Auto series
 * The Legend of Zelda series (the later games, at least, with some variation)
 * Final Fantasy II. Once you get the canoe you can go to any location on the planet except for Deist and the Black Mask Island and Palamecia, but be prepared for Beef Gates to curb stomp you back onto the plot.
 * Legend of Mana. All of the 60 or so quests are optional but playing through them rewards you with artifacts that you choose where to place on the World Map to create the Adventure Towns. There are very few cues to determine where to go or who to talk to to progress, leading to long sessions of wandering around the world looking for what to do next. While highly addicting due to its incredible amount of customization options and details, the lack of a strong central narrative to tie the 3 Main Arcs together was criticized.
 * The Dead Rising series
 * The Elder Scrolls IV: Oblivion
 * The Escape Velocity series
 * The Fallout series
 * Fallout: New Vegas floats between Level 4 and Level 5. You can pretty much go anywhere right from the start, but if you don't follow the main questline (which sends you in a big loop around the southern part of the map), you'll run into something nasty that would get a new player killed. A second-time player, however, one will know the hidden safe paths and be able to travel as he pleases.
 * The same strategy of threat placement keeps the player from walking straight to San Francisco in Fallout 2 as well. And, unlike in New Vegas, player's skill can not make up for it due to the simpler 2D engine, making Save Scumming the only way to greatly depart from one of the intended paths. An initially blank World Map does not help either.
 * Final Fantasy VI, once you hit the World of Ruin.
 * Final Fantasy X-2. Technically most of the game is optional, but you'll need to do most of the side quests to be at a decent level.
 * Mass Effect: There are plenty of sidequests to keep you busy, and you can do the main missions in any order you want. Do enough main missions, and more are unlocked.
 * Mass Effect 2 belongs either here or further down the list. You are provided with an objective and a list of Party Members you can recruit to help you achieve it, some of them optional; there are also Side Quests which focus on those party members' Character Development and thus increase the likelihood of them having clear heads and steady hands once things start getting real. Of course, it also starts with a heavy-handed dose of Railroading in which you are forced to work for The Mafia just because they brought you Back from the Dead, so, there's that.
 * Guild Wars has a main storyline for all three campaigns, but you can freely explore most areas of the world, with the chance to explore high end areas as a low-level character...if you can survive the onslaught of level 20 mobs in between (example: the run from Northen to Southern Shiverpeaks).
 * Guild Wars 2: Both open world exploration and storyline are favored. Sidequests are replaced by Events, sort of what Side Quests would be like if their backstory was actually played out and by trait gathering, which is Side Quests without exclamation marks
 * Mercenaries
 * The Baldur's Gate series. Works very much like the Mass Effect example above.
 * Romancing SaGa.
 * Crackdown and its sequel.
 * The Precursors.
 * Freelancer has a storyline which cannot be easily departed from (there are a chain of level caps, all the gear is level-limited, and you can't Open The Sandbox until you complete the earlier quests), but the storyline doesn't take much time, and after that it's a true Wide Open Sandbox. Of course, it's also not hard to completely max out your ride and have the entire map explored, at which point it becomes hard to set compelling goals.
 * In Final Fantasy Tactics A2 literally only 20 of 301 missions (more if you count non-mission encounters with monsters or other clans and Brightmoon Tor) are main-story missions. Completing them all without any of the experience, unlocked classes, or loot (and thus gear) from non-story missions is nearly impossible but even then you can easily make it with only a very small fraction of missions completed if you have a small clan.
 * Remarkably, A Spy in Isengard managed to reach a high level five, maybe even a low six, with a gamebook. You could go anywhere on the map, at your own pace and schedule, and return to locations you had previously visited if you wanted. There was an overarching quest, with a time limit, but if you didn't finish in time, that was merely a suboptimal ending, not a total defeat. Also, you could choose one of three different possible end points, although you did have to choose at the beginning. Some of the other books in the series had similar mechanics, although few would rank as high on the scale, but some, like Treason at Helm's Deep, which would probably constitute a level two, were much more linear. Since your typical gamebook was a level two or three, this was a pretty impressive feat.
 * The first book in the series, Night of the Nazgûl, was also about a five technically, but since a lot of the location passages referred to the same encounter passages, it was like playing in a Wide Open Sandbox where you could go anywhere, but almost everywhere was identical to at least several other locations.
 * S.T.A.L.K.E.R.

Level 6

 * Animal Crossing: While the game does give you the initial goal of paying off the mortgage on your house, that doesn't last long, and is only the very tip of the iceberg of what there is to do in this game. (You are also in no way forced to ever pay it off.)
 * Dwarf Fortress, true to its nature, has no win condition, only a neverending series of lose conditions, all of which can be suspended indefinitely with relative ease. Adventure mode is even more wide open, but the lack of options that goes alongside the lack of limitations makes it more of a Level 2 in practice.
 * The Elder Scrolls titles typically fall into this category. In Daggerfall, for example, it's very easy to forgo the main quest, especially since there is a time limit respond to a PC's letter. Beyond that, you are on your own to explore and seek out sidequests. Morrowind is much the same—there's a main quest, you have a pointer to it, and it's 100% optional. (The Expansion Packs for it shade down into Level 5, being far more structured and having less non-main-quest content.) As for Skyrim...well, Skyrim may be THE definition of open world.
 * Elona: Like Dwarf Fortress's Adventure Mode, except more pretty. You can do the main quest, but you're not forced into it, you can take as long as you like, and you can even turn it off.
 * The Sims In Sims 3, 'story mode' alludes to often dichotomous plotlines for the initial housesholds when you start a new game, in true soap opera fashion, but there's little chance of any of these storylines proceeding without direct player intervention, and player-created families aren't included. There's no 'sandbox mode', but there are options to make the game even more open than the ostensible 'story mode' is. The earlier games are similar, although there are console versions that are somwhat more linear.
 * World of Warcraft: While there are plenty of quests to give your character something to do, there is no overarching motivation or plot for your character beyond the eternal pursuit of loot.
 * Cataclysm brings it down a notch - now there is a defined quest path through each specific zone and skipping parts of the zone is mostly impossible. But it still stays open in choosing the zone - this is only limited by character's level.
 * Creatures
 * Spore's Space Stage. Your homeworld gives you storyline missions, but you're free to ignore all but the introduction before going off to play with your tools in the celestial sandbox. You just have to watch out for your homeworld getting destroyed by aliens, as they never defend themselves.
 * Turrets, my friend, turrets. Note also that this is a rare aversion of Sci-Fi Writers Have No Sense of Scale, at least in terms of how crazy huge a galaxy is (travel is still ludicrously fast for gameplay reasons.)
 * Viva Pinata (at least Trouble in Paradise)
 * Minecraft looks to be shaping up to be at this level. Though Notch states that he wants a "climax" of some sort, he also speaks of "emergent" plot and gameplay; it would probably be a surprise if you had to try to "win".
 * Most custom Adventure maps tend towards 1 or 2 if they have an actual plot. Wool collection maps are usually 3 or 4.
 * SimCity will let you build anything from a tiny mountain village to a huge metropolis, and from a dystopian wasteland to a paradise. As long as you avoid bankruptcy, the game goes on. Even if you burn the whole city to the ground.
 * Most early simulation games are like that. You just get thrown into the game world with a hinted goal of "get rich". If there is a back story, it's All There in the Manual. This is probably the only genre that tends to go down the scale in sequels.
 * EVE Online has player-run corporations, with all the various positions and routes for advancement that entails, and this economic system also allows for many forms of criminal activity and freelance work.
 * LSD Dream Emulator has no plot besides the fact that it's supposedly a dream in one constant world (and it's pretty big) that changes the longer you play.
 * Star Control II. It has a main quest. But even finding out what that is has to be done via exploration, let alone completing it. You're given the rather vague goal of "destroy the Ur-Quan", which is a tall order, considering that they have thousands of ships and you have... one. No, wait; two. You have to fly around a galaxy with hundreds of star systems and look for other civilizations who might be convinced to help in the fight against the Ur-Quan.
 * Elite and the Fan Remake Oolite.
 * Garry's Mod
 * Egosoft's X-Universe series started as a level 5 (Beyond the Frontier gave you fairly clear indications on what to do next, and trading/building was finalized to doing the final quest), but quickly evolved into a type 6. In the later games, the player is given the choice of starting an entirely plotless game, where mission scripting is completely disabled, just so they can exploit the game's universe to their heart's content.
 * The Saints Row series, because there are so many diversions from the main missions.
 * The Russian FPS/RPG hybrids Xenus series (In America/Western Europe, the first game is known as Boiling Point: Road to Hell and the second White Gold: War in Paradise), which feature a rather open Main Quest with different ways to progress plus lots of sidequests for different factions in a large, open world.
 * Yume Nikki technically has player objectives and an ending, but you'd never know it unless you read a walkthrough. Most of the gameplay simply involves aimlessly wandering around the protagonist's Dream World, and soaking in all the deliciously creepy atmosphere along the way.
 * Terraria. You spawn with some basic tools and a Guide who tells you what you can build with any materials you have on hand and gives you tips on how to survive in the long term. Otherwise, it's up to you.
 * Second Life is pretty much the ultimate. Its not really even a game. You can design your own objects (even importing designs from sophisticated real world 3D design tools such as Blender and Maya) you can write scripts in an actual scripting language, you can even code your own Viewer for the world. The game's content is mostly generated by the players based on a real economy. But what really puts it at the extreme end of the spectrum is that you can build your own games and/or play games built by other "players." In fact, for the first 6 or 7 years, the only actual games to play were created by users.
 * The only sandbox more extreme than this is Open Sim which is the open source code released by Second Life's creators. Its doesn't even feature the Linden's regulations.