Sokoban (倉庫番, Sōko-ban, lit. 'warehouse keeper') is a puzzle video game in which the player pushes boxes around in a warehouse, trying to get them to storage locations. The game was designed in 1981 by Hiroyuki Imabayashi, and first published in December 1982.
The game is played on a board of squares, where each square is a floor or a wall. Some floor squares contain boxes, and some floor squares are marked as storage locations.
The player is confined to the board and may move horizontally or vertically onto empty squares (never through walls or boxes). The player can move a box by walking up to it and push it to the square beyond. Boxes cannot be pulled, and they cannot be pushed to squares with walls or other boxes. The number of boxes equals the number of storage locations. The puzzle is solved when all boxes are placed at storage locations.
|1982||Sokoban (倉庫番)||Japan||NEC PC-8801||Thinking Rabbit||Cassette tape|
|1983||Sokoban [Extra Edition] (倉庫番[番外編])||Japan||NEC PC-8801||PCマガジン||Type-in program|
|1984||Sokoban 2 (倉庫番2)||Japan||NEC PC-8801||Thinking Rabbit||Cassette tape|
|1988||Soko-Ban||US||IBM PC and compatibles||Spectrum HoloByte||Floppy|
|1989||Soko-ban Perfect (倉庫番Perfect)||Japan||NEC PC-9801||Thinking Rabbit||Floppy|
|1990||Boxyboy||Japan, US||Turbografx-16/PC Engine||NEC||HuCard|
|1991||Soko-ban Revenge (倉庫番Revenge)||Japan||NEC PC-9801||Thinking Rabbit||Floppy|
|2016||Sokoban Touch (倉庫番Touch)||Japan, US||Android and Apple iOS||Thinking Rabbit||Digital distribution|
|2019||Minna No Sokoban (みんなの倉庫番)||Japan||Nintendo Switch and PlayStation 4||Unbalance Corporation||Digital distribution|
|2021||The Sokoban||US||Nintendo Switch and PlayStation 4||Unbalance Corporation||Digital distribution|
Sokoban was created in 1981 by Hiroyuki Imabayashi. The first commercial game was published in December 1982 by Thinking Rabbit, a software house based in Takarazuka, Japan. Sokoban was a hit in Japan where it sold more than 400,000 copies before being released in the United States. In 1988, Sokoban was published in US by Spectrum HoloByte for the Commodore 64, IBM PC compatibles, Amiga, and Apple II as Soko-Ban.
Implementations of Sokoban have been written for numerous computer platforms, including almost all home computer and personal computer systems. Different versions also exist for video game consoles, mobile phones, graphic calculators, digital cameras and electronic organizers.
Sokoban can be studied using the theory of computational complexity. The problem of solving Sokoban puzzles was first proved to be NP-hard. Further work showed that it was significantly more difficult than NP problems; it is PSPACE-complete. This is of interest for artificial intelligence (AI) research because solving Sokoban can be compared to the automated planning required by some autonomous robots.
Sokoban is difficult not only because of its large branching factor, but also because of its large search tree depth. Some level types can even be extended indefinitely, with each iteration requiring an exponentially growing number of moves and pushes. Skilled human players rely mostly on heuristics and are usually able to quickly discard a great many futile or redundant lines of play by recognizing patterns and subgoals, thereby drastically reducing the search effort.
Some Sokoban puzzles can be solved automatically by using a single-agent search algorithm, such as IDA*; enhanced by several techniques that make use of domain-specific knowledge. This is the method used by Rolling Stone, a Sokoban solver developed by the University of Alberta GAMES Group. Festival was the first automatic solver to solve all 90 levels in the standard benchmark test suite. However, the more complex Sokoban levels are out of reach even for the best automated solvers.
Several puzzles can be considered variants of the original Sokoban game in the sense that they all make use of a controllable character pushing boxes around in a maze.