A tile-matching video game is a type of puzzle video game where the player manipulates tiles in order to make them disappear according to a matching criterion. In many tile-matching games, that criterion is to place a given number of tiles of the same type so that they adjoin each other. That number is often three, and these games are called match-three games.
The core challenge of tile-matching games is the identification of patterns on a seemingly chaotic board. Their origins lie in late 1980s games such as Tetris, Chain Shot! (SameGame) and Puzznic. Tile-matching games were made popular in the 2000s, in the form of casual games distributed or played over the Internet, notably the Bejeweled series of games. They have remained popular since, with the game Candy Crush Saga becoming the most-played game on Facebook in 2013.
Tile-matching games cover a broad range of design elements, mechanics and gameplay experiences. They include purely turn-based games but may also feature arcade-style action elements such as time pressure, shooting or hand-eye coordination. The tile matching mechanic is also a minor feature in some larger games. Video game researcher Jesper Juul therefore considers tile matching to be a game mechanic, rather than a distinct genre of games.
The mechanism of matching game pieces to make them disappear is a feature of many non-digital games, including Mahjong solitaire and Solitaire card games. Jesper Juul traces the history of tile-matching video games back to Tetris and Chain Shot!, published in 1984 and 1985. While both focus on pattern matching, they differ in important design points such as time pressure, tile manipulation and match criteria. A second generation of influential matching games - Puzznic, Columns, Dr. Mario and Plotting - was published in 1989 and 1990.
Games building on Dr. Mario's mechanics include Puyo Puyo (1991), Baku Baku Animal (1995) and Puzzle Fighter (1996). Building on the shooting mechanic introduced in Plotting, Dr. Mario also influenced Puzzle Bobble (1994), which in turn inspired Puzz Loop (1998), Hexic and Zuma (2004), and Luxor (2005).
Columns was the basis of a line of development of tile matching games based on shifting or swapping tiles. It includes Yoshi's Cookie (1992) and Panel de Pon (1995), which introduced the swapping mechanic.
The first of what eventually became known as "match three" games, where the goal is to create clusters of three or more identical items on a grid, was Shariki (1994). It led directly to the successful Bejeweled (2000), which became a series and inspired similar games including Zoo Keeper (2003), Big Kahuna Reef (2004), Jewel Quest (2004), and Chuzzle (2005). The origins of Candy Crush Saga (2012) arose from trying to create a game like Bejeweled, and became one of the most financially-successful mobile games, popularizing the tile-matching approach with microtransactions, and spurring on the growth of the mobile market.
Many casual tile matching games continue to be published. Their development is characterized by gradual evolution, where new games makes only small changes, if any, to a formula known from previous games. In the highly competitive market for downloadable casual games, new entries must be familiar enough to appeal to players of earlier games, but innovative enough to differentiate the new game from earlier ones. This leads to developers, according to Juul, "simultaneously trying to out-innovate and out-clone each other".
Tile-matching games that are set in a fictional background are normally based in a "bright and positive" fiction, as opposed to the warlike background of strategy games or the fantasy background of massively multiplayer games.
Tile matching game mechanics have been combined with other mechanics to produce a great variety of puzzle game experiences. This section discusses a number of these mechanics.
Many tile-matching games are timed - that is, new tiles are continuously added and the player is under pressure to make matches before the board fills up.
Untimed (turn-based) games, in which new tiles are added only after the player has made a move, used to be the exception, although the 1985 game Chain Shot! already had an untimed mode. The addition of an untimed mode to Bejeweled! was integral to that game's success, as well as one of its most important influences on subsequent games, as it made the game more accessible to less skilled players.
Tiles may be arranged on a horizontal surface or vertically (that is, stacked atop one another, and dropping down when tiles below are removed). In the latter case, some games allow moving or rotating new tiles as they fall down from the top of the playing area, as in Tetris or Dr. Mario; or they may allow only the manipulation of tiles that have already fallen, as in Yoshi's Cookie.
Panel de Pon introduced, and Bejeweled popularized the mechanism of tile swapping, in which tiles may be moved by exchanging the position of two adjacent tiles. Another frequently used tile manipulation method is having the player shoot the tiles onto the board, such as in Plotting and its descendants including Zuma. The first method, which allows only moves that create a match, results in a more strategic, thoughtful style of play, whereas the second method requires hand-eye coordination in addition to pattern recognition skills, and makes for a more hectic style of play.
Tetris and its derivatives are somewhat unusual in that they feature irregularly shaped tiles composed of squares, which match with all other tiles no matter what their color is. In other games, the tiles are most often uniformly square or round, and are distinguished for the purpose of matching by color or some other decoration. This shifts the game's focus towards pattern recognition and away from the act of manipulating the tiles.
Tetris's matching criterion of filling a full line on the board has not been taken up by most other tile-matching games. In most games, a match occurs when a given number (often three) or more tiles of the same type adjoin each other. At that time, they are removed from the board. A great number of gameplay variations are possible by introducing special tiles that behave differently, such as by being indestructible, or by destroying surrounding tiles when involved in a match.
In most tile-matching games, players obtain points for each match. Higher scores are awarded for more difficult matches, such as those involving a greater number of similar tiles.
In most tile-matching games, new tiles are randomly added to the board continuously, either turn by turn or in real time. This may continue indefinitely or for a given period of time or number of turns.
The player must continuously remove the newly added tiles through matching. The game may end with a loss when the board is filled with tiles or if there are no more possible matches. It may end with a victory when the player clears the board or reaches a given score.
Among downloadable casual video games, according to a survey referred to by Juul, tile-matching games were the second most popular game type in 2004 and by far the most popular in 2005. After that, their popularity declined: they were the fourth most popular of several genres in 2006 and 2007, and in 2008 a games publisher referred to them as a "niche" genre. But as they became well known and therefore assumed to be immediately playable by many people, tile-matching games migrated to other, more ubiquitous distribution channels such as cell phones and smartphones.
Despite their commercial popularity, tile-matching games are among the games with the lowest status among video game enthusiasts, to the point where reviewers have advised gamers not to be ashamed of playing them. This may be because critics consider that there are too many of these games, which differ only slightly from each other. It may also be because, as casual games, tile-matching games are designed to be easily accessible and easy to play, which conflicts with a traditional video gaming ethos that demands games to be challenging and punishing.
Match-three games are NP-hard when generalized to an n × n playfield and played such that the player knows in advance all the tiles that will appear, with no random chance involved. In particular, it is NP-hard to determine: