2½D



Straddling the line between "style" and "genre," 2½D is an uncommon but generally recognized term. While there is some ambiguity among gamers as to what, exactly, constitutes "2½D," it is most commonly used to refer to one thing: Two-dimensional, side-scrolling Platformers with some three-dimensional elements.

In a "traditional" platformer, players can only move in four directions: up, down, left, and right. That's two dimensions (height and length). 2½D games mess with this formula by adding a third dimension, but not dedicatedly. Players can still only control their character in four directions (generally), but there are some options as to where the extra half a dimension comes from:
 * The player can only move in two dimensions, but the path doesn't have to. The "plane" that the 2D character follows curves through three-dimensional space, and the Player Character follows along that. This is by far the most common, and the trait that is most likely to get a game labeled "2½D".
 * Off-path objects. While the player is stuck on one path, there are things outside the path that can be interacted with.
 * Layers: There are things visible in both the background and foreground, and it is possible to switch between paths to reach the goal. This gives the level a layered feeling, like a delicious, platforming pastry.
 * Other tactics that are more localized.

Sometimes, if an otherwise 3D game takes the time to have a 2D interlude, those segments will sometimes be referred to as "2½D." Occasionally, 2D Platformers that simply use 3D graphics will be referred to as "2½D", though that is less common.

In older material the term 2.5D is sometimes used in reference to 3D games that use 2D surfaces, with various graphical tricks used to make it seem 3D (e.g. Doom). This specific usage died with the Game Boy Advance, the last well-known platform to use this technology, but it overlaps with the sense of only moving in two dimensions. The term can also be used for Isometric Projection or Sprite Polygon Mix.

See also Background Boss, which may or may not utilize 2½D characteristics.

Let's not dwell on the confusing terms that are sure to arise for 2½D games on the Nintendo 3DS....

Compare Fixed Camera.

Examples of games that are 2½D or use 2½D segments:

Adventure Games

 * Super Castlevania IV allowed Simon to use gates in the first level to go in front of, or behind, a fence. Doing so would allow him to traverse obstacles in front of or behind said fence. There were other similar parts through the game as well, including enemies that appeared from the fore- or background.
 * The DS The Legend of Zelda games have managed to blend this trope with the traditional Zelda Three Quarters View. You can only interact with things on your plane, while going up or down allows you into others, while everything is rendered in 3D. When you are on your boat/train, you gain the ability to fire at things with your canon in full 3D, but you literally use a 2D map to plot your course.
 * Shantae: Risky's Revenge features a "layered" approach, where you can hop between the foreground, regular-ground, and background in certain areas.

Fighting Games

 * Classic Neo Geo fighter Fatal Fury (and its descendants) allow a player to jump from the foreground to the background, and to launch attacks back and forth. The jumps were replaced by slides and the system was progressively refined over the course of the series until being completely dropped in Mark of the Wolves.
 * As does Savage Reign, allowing an upper and lower plane. Especially notable is that in some stages, the "upper plane" consists of hanging off something. While fighting.
 * Modern fighting games like Street Fighter IV and Mortal Kombat 9 feature 2D combat with 3D engines, allowing different cinematic views during certain moves or scenes. (Such as Ultra Moves in the former, and Fatalities in the latter.)
 * The Bleach fighting games for the Nintendo DS allow you to 'line jump' between two planes to avoid attacks and play keep-away.

Platformers

 * Shadow Complex, an Xbox LIVE Downloadable arcade is a 3D setting with a 2D Movement area.
 * Virtual Boy Wario Land has foreground and background areas given a 3-D effect with the system's dual projections. There's trampoline blocks in specific places Wario can use to jump between the two layers, and all of the bosses use foreground/background movement as part of their attacks. The first boss demonstrates this perfectly when flinging his ball-and-chain at Wario from the background- the spiked ball appears to come hurtling towards YOU, the player, stopping just short of crashing through the fourth wall.
 * Mighty Morphin' Power Rangers: The Movie: In the game for the SNES, you could press the shoulder buttons to flip to the "back" or the "front" to avoid obstacles, such as in the very first level to avoid cars. The enemies could do this as well.
 * Bug! An experimental take on 2½D, the titular character could move left and right, or "in and out" of the screen, but not both at a time. Vertical movement was possible at all times.
 * Duck Dodgers in the 24th and a Half Century!, a Nintendo 64 game, was a 3D platformer with 2½D sections.
 * Kirby 64 The Crystal Shards, mostly with the 3D curving path elements.
 * The Klonoa series, which uses all of the tricks listed above and more. Klonoa can even be controlled in three dimensions, even if he's limited to only two.
 * The New Super Mario Bros. games are a bit like this: 2D side scroller, but 3D characters.
 * Pandemonium was a 2D platformer in a 3D environment. Stuff like spiral stairs, or two paths at different heights splitting into different directions, was common.
 * Some of the two-dimensional segments of Super Mario Galaxy are like this.
 * In Super Mario Galaxy 2, there are levels which go from 3D to 2D just by walking past a certain point. It's the entire gimmick of the Rightside Down Galaxy, but the Flash Black Galaxy and Honeybloom Galaxy have elements (former starts 3D, becomes 2D and turns back to 3D) while the latter has 3D for a secret star area. Bowser's Gravity Gauntlet is this taken to the extreme.
 * Tomba
 * Trine
 * The Super NES Scooby Doo game had doorways that Shaggy and Scooby could enter by walking toward or away from the player.
 * Yoshi's Story on the N64 is another fine example of a 2D platformer with 3D levels, Yoshis, and such.
 * The 2D segments in Sonic Unleashed are really this. The only thing keeping them from being 3D is the complete inability to move to the side under your own power (which you have in the 3D segments) -- you can easily be, and often are, moved in the third direction by bumpers, spiral paths, and paths with loop-de-loops.
 * Sonic Colors also does this, but with greater focus on the 2D platforming aspect.
 * Sonic Generations plays with this trope to varying extents with its two playable characters: Modern Sonic's use is similar to Sonic Unleashed and Sonic Colors with its 3D/2.5D shifts at certain points of a given level; Classic Sonic's use, on the other hand, is all 2.5D. The 3DS version, meanwhile, is entirely 2.5D except for parts of the final boss battle.
 * The Sonic Rush Series series plays in 2D (except for bosses, in which the paths curve and twist, thus being 2.5D), but Sonic and Blaze are cel-shaded 3D models. This allows segments where Sonic and Blaze are "closer to or further away" from the screen during certain level specific gimmicks.
 * The underrated Sonic Rivals series for the PSP has 3D graphics, and linear paths that twist and curve.
 * Sonic CD had Metallic Madness zone, where you could go behind certain walls to progress and get powerups, before going back infront again to continue the level proper.
 * Mega Man X 7 danced between 2D and 3D without much warning. X8 might be a better example, as it stayed in 2D but had some occasional 3D-esque moments.
 * Super Mario Bros 3 did this with a secret warp near the beginning of the game. Crouching on a certain block would make you fall behind the block, which allowed Mario to walk behind bushes, and even the end-of-level "curtains".
 * Super Mario World had, in various castle levels, fenced grates that Mario (and Koopa Troopers) could climb and switch from the back to the front.
 * Goemon's Great Adventure is done in full 3D, but the character can only move along one plane. The paths curve and branch off, but outside of towns, left and right are your only choices.
 * Viewtiful Joe and its sequel are both like this.
 * Donkey Kong Country Returns, as pictured above.

Role Playing Games

 * Some gaming media outlets classify the Paper Mario series as this, depending on whose reviews you read. While Mario can move in three dimensions, the areas he moves through tend to be narrow and reminescent of traditional sidescrolling levels—and Paper Mario: The Thousand-Year Door gets a lot of milage out of the "Layers" variant. Super Paper Mario only complicates things by being a 2D platformer you can flip to 3D in some instances.
 * There's an example of the "3D game with a 2D interlude" variety in the 2D platforming stages of KingdomHeartsReCoded.
 * Pokémon Diamond and Pearl, despite being nicknamed the "3D Generation" of the main series, is 2.5D; the player walks around in a two-dimensional grid based world, but structures around the player change perspective as (s)he moves around. The one exception to this dynamic is the Distortion World in Pokémon Platinum.
 * Pokémon Black and White, on the other hand, are the first main series games to feature full 3D, more or less. The biggest difference between the 3D featured in Generation V and the one in Generation IV is that the camera plays around in the former, while being completely fixed in the latter. It can also be even argued that Generation IV is itself the first true 3D generation, as there are a few hacks for those games that allows you to play with the camera angles, proving that they have fully 3D worlds.
 * Dragon Saga has an interesting take on this. The game is in full 3D and some sections of the game allow 3D movement. However, most combat areas only allow the player character to face and aim attacks to the left or right with movement towards or away from the screen causing them to slide sideways. Needless to say the few sections of the game that allow 3D combat take some getting used to and reveal that the hit boxes for attacks are always much longer on one axis than on others.

Shoot 'Em Up

 * Einhander. Notable for playing like a linear 2D side scroller, but your homing missiles can home in on enemies in the foreground and background.

Strategy Games

 * Diggles has a fully fledged 3D-engine, but you can only dig and build in a vertical plane reaching down into the earth.