KSokoban, an implementation of Sokoban for GNU/Linux. In this version, the red rubies play the role of the boxes described in the text.

Level 1 of the PC version of Sokoban

Sokoban (倉庫番, Japanese for "warehouse keeper") is a transport puzzle in which the player pushes boxes around a maze, viewed from above, and tries to put them in designated locations. Only one box may be pushed at a time, not two, and boxes cannot be pulled. As the puzzle would be extremely difficult to create physically, it is usually implemented as a video game. Screenshot from KSokoban (GPL program). ... Screenshot from KSokoban (GPL program). ... Unix systems filiation. ... screenshot of the first level of the PC game Sokoban; made by me This is a screenshot of a copyrighted computer game or video game. ... screenshot of the first level of the PC game Sokoban; made by me This is a screenshot of a copyrighted computer game or video game. ... Transport puzzles are logistical puzzles, which represent real-life transport problems. ... Public hedge maze in the English Garden at Schönbusch Park, Aschaffenburg, Germany A small maze A maze is a tour puzzle in the form of a complex branching passage through which the solver must find a route. ... For the Wikipedia term see Wikipedia:Userboxes An empty corrugated box An elaborate wooden box Boxes are highly variable receptacles. ... Namcos Pac-Man was a hit, and became a universal phenomenon. ...

Sokoban was created in 1980 by Hiroyuki Imabayashi, and was published in 1982 by Thinking Rabbit, a software house based in Takarazuka, Japan. Thinking Rabbit also released three sequels: Boxxle, Sokoban Perfect and Sokoban Revenge. Year 1980 (MCMLXXX) was a leap year starting on Tuesday (link displays the 1980 Gregorian calendar). ... Year 1982 (MCMLXXXII) was a common year starting on Friday (link displays the 1982 Gregorian calendar). ... Thinking Rabbit was a software house based in Takarazuka, Japan, and are the original publishers of Sokoban. ... A software house is a commercial entity whose primary products are composed of software, i. ... Takarazuka (宝塚市; -shi) is a city located in Hyogo, Japan. ...

Implementations of Sokoban have been written for numerous computer platforms, including almost all home computer and personal computer systems. Versions also exist for several hand held and video game consoles, including mobile phones. Many other puzzle games, such as Chip's Challenge and Rocks and Diamonds, implement Sokoban-based gameplay. The roguelike computer game NetHack contains a sequence of dungeon levels deliberately designed to simulate a Sokoban game. In computing, a platform describes some sort of framework, either in hardware or software, which allows software to run. ... Children playing on a Amstrad CPC 464 in the 1980s. ... A handheld game console is a lightweight, portable, electronic device for playing video games. ... A video game console is an interactive entertainment computer or electronic device that manipulates the video display signal of a display device (a television, monitor, etc. ... Screenshot of the first level in Lynx CC Chips Challenge is a tile-based, puzzle video game for several systems, including the hand-held Atari Lynx, ZX Spectrum[1], DOS, and Windows (included in the Microsoft Entertainment Pack and Best of Microsoft Entertainment Pack). ... Rocks and Diamonds, more commonly known as Rocks n Diamonds, is a long running computer game which runs on DOS based, Windows based, or Unix based systems. ... A roguelike is a computer game that borrows some of the elements of the 1980s computer game Rogue. ... A computer game is a game composed of a computer-controlled virtual universe that players interact with in order to achieve a defined goal or set of goals. ... This article is about the role-playing game. ... The dungeons of Blarney Castle. ... In computer and video games, a level (sometimes called a stage, course, episode, round, world, map, wave, board, phase, or landscape) is a separate area in a games virtual world, in modern games typically representing a specific location such as a building or a city. ...

Sokoban variants

Several puzzles can be considered variants of the original Sokoban game, in the sense that they all make use of a controllable character who pushes boxes around a maze.

Alternative Tilings: In the standard game, the mazes are laid out on a tiling of squares. Several variants apply the rules of Sokoban to mazes laid out on other tilings. Hexoban uses a tiling of regular hexagons and Trioban a tiling of equilateral triangles. In geometry, the Square tiling is a regular tiling of the Euclidean plane. ... In geometry, the hexagonal tiling is a regular tiling of the Euclidean plane. ... In geometry, the triangular tiling is a regular tiling of the Euclidean plane. ...

Multiple pushers: In the variants Multiban and Interlock the player can control multiple characters.

Alternative goals: Several variants adjust the requirements for completing a level. For example, in Block-o-Mania the boxes are different colours and the goal is to push them onto squares which match their colours. Sokomind Plus implements a similar idea, with boxes and target squares uniquely numbered. In Interlock and Sokolor, the boxes are also different colours, but the goal is to move them so that similarly coloured boxes are adjacent. In CyberBox, each level has a designated exit square, and the goal is to reach that exit.

Additional game elements: Sokonex, Xsok, Cyberbox and Block-o-Mania all add new elements to the basic puzzle. Examples include holes, teleports, moving blocks and one-way passages.

Scientific research on Sokoban

Sokoban can be studied using the theory of computational complexity. The problem of solving Sokoban puzzles has been proven to be NP-hard^[1] as it is part of a more general class of motion planning problems where the porter is allowed to push and/or pull one or more boxes at a time. This is interesting also for artificial intelligence researchers, because solving Sokoban can be compared to designing a robot which moves boxes in a warehouse. Further work has shown that solving Sokoban is also PSPACE-complete^[2]. As a branch of the theory of computation in computer science, computational complexity theory describes the scalability of algorithms, and the inherent difficulty in providing scalable algorithms for specific computational problems. ... In computational complexity theory, NP-hard (Non-deterministic Polynomial-time hard) refers to the class of decision problems that contains all problems H such that for all decision problems L in NP there is a polynomial-time many-one reduction to H. Informally this class can be described as containing... Garry Kasparov playing against Deep Blue, the first machine to win a chess game against a reigning world champion. ... In complexity theory, PSPACE-complete is a complexity class. ...

Sokoban is difficult not only due to its branching factor (which is comparable to chess, but still much lower than that of go), but also its enormous search tree depth; some levels require more than 1000 "pushes". Skilled human players rely mostly on heuristics; they are usually able to quickly discard futile or redundant lines of play, and recognize patterns and subgoals, drastically cutting down on the amount of search. In computing, tree data structures, and game theory, the branching factor is the number of children of each node. ... Chess is a recreational and competitive game for two players. ... Go is a strategic East Asian board game for two players. ... Tree search algorithms are specialized versions of graph search algorithms, which take the properties of trees into account. ... For heuristics in computer science, see heuristic (computer science) Heuristic is the art and science of discovery and invention. ...

Some Sokoban puzzles can be solved automatically by using a single-agent search algorithm, such as IDA*, enhanced by several techniques which make use of domain-specific knowledge^[3]. This is the method used by Rolling Stone, a Sokoban solver developed by the University of Alberta GAMES Group. The more complex Sokoban levels are, however, out of reach even for the best automated solvers. Iterative deepening depth-first search is a states-space search strategy, that visits each node in the search tree in the same order as depth-first search but does so by gradually increasing the maximum depth limit of the search iteratively. ... The University of Alberta (U of A) is a public coeducational research university located in Edmonton, Alberta, Canada. ...

References

1. ^ M. Fryers and M.T. Greene (1995). "Sokoban". Eureka (54). 
2. ^ Joseph C. Culberson, Sokoban is PSPACE-complete. Technical Report TR 97-02, Dept. of Computing Science, University of Alberta, 1997. Also: http://web.cs.ualberta.ca/~joe/Preprints/Sokoban
3. ^ Andreas Junghanns, Jonathan Schaeffer, Sokoban: A Case-Study in the Application of Domain Knowledge in General Search Enhancements to Increase Efficiency in Single-Agent Search. Artificial Intelligence, special issue on search, 2000.

See also

• Logic puzzle
• Sliding puzzle
• Wonderland
• Chip's Challenge

A logic puzzle is a puzzle deriving from the mathematics field of deduction. ... Sliding puzzles or sliding block puzzles challenge a player to slide usually flat pieces along certain routes (usually on a board) to establish a certain end-configuration. ... An in-game screenshot of Wonderland. ... Screenshot of the first level in Lynx CC Chips Challenge is a tile-based, puzzle video game for several systems, including the hand-held Atari Lynx, ZX Spectrum[1], DOS, and Windows (included in the Microsoft Entertainment Pack and Best of Microsoft Entertainment Pack). ...

External links

• Official Sokoban site (in Japanese)
• The University of Alberta Sokoban page
• Erim Sever Sokoban web page - Sokoban history, rules, references, and so forth
• Soko-Ban at MobyGames