Sokoban

Template:Short description Template:Use mdy dates Template:Infobox video game series Template:Nihongo foot is a puzzle video game series in which the player pushes boxes in a warehouse to get them onto storage locations. The game is viewed from a top-down perspective. Boxes can only be pushed, never pulled, and only one box can be pushed at a time. The principal challenge is planning moves correctly to avoid deadlocks, i.e., situations where a box or the player becomes permanently trapped, making the puzzle unsolvable.

Hiroyuki Imabayashi created the first Sokoban game as a hobby in 1981; his company, Thinking Rabbit, commercially released the first enhanced version in December 1982. This initial title became a bestseller in Japan. Between 1982 and 2000, Thinking Rabbit and its licensed partners developed new titles for various platforms. The series made its international debut in 1988 with the U.S. release Soko-Ban. In 2001, Falcon acquired the Sokoban rights and the Thinking Rabbit brand, becoming the series' main developer and licensor; since then, new titles have been published either by Falcon under the Thinking Rabbit brand or by licensed partners.

Over its history, the series has sold over 4.1 million copies worldwide, with more than 40 official games released across various platforms. Reviewers have consistently praised the game's simplicity, its addictive and challenging nature, and the level of thought required. However, it has been criticized for a lack of variety.

Due to the creation of numerous clones, the name "Sokoban," a registered trademark, has become genericized to describe the genre. The series has inspired thousands of custom puzzles, as well as Sokoban-like games. Its core concept of pushing objects to targets has been widely used in puzzles within other video games. Moreover, Sokoban puzzles have been studied in the fields of computational complexity and artificial intelligence.

Gameplay

File:Sokoban ani.gif

The puzzles in Sokoban require the player to push boxes to designated spots (shown as red dots in the animation) in the game world.

Sokoban takes place in a warehouse viewed from above and composed of walls and floor squares. A floor square may be empty, occupied by the player, or occupied by a box. Some floor squares are storage locations. The number of storage locations equals the number of boxes. The objective of the puzzle is to push all boxes onto storage locations.

The player can move one square at a time, either horizontally or vertically, onto an empty floor square. Boxes and walls block the player's movement, but the player can walk up to a box and push it to an empty square directly beyond it. If a box is pushed against a wall or another box, it does not move. Pulling boxes is not possible.

Sokoban requires players to plan several moves ahead and consider all possible outcomes. Careful decision-making is essential to avoid pushing a box into a position where it becomes permanently trapped against a wall, another box, or in a dead end. Such situations create deadlocks that make the puzzle unsolvable, regardless of future moves.

History

In 1981, Hiroyuki Imabayashi created the first Sokoban game for the NEC PC-8001 as a hobby, featuring text-based graphics and five original levels. The core mechanic was inspired by Hudson Soft's 1980 game Aldebaran #1 for the MZ-80K, where players pushed luggage to block radiation. Imabayashi envisioned a warehouse setting where incorrect box placement could make further progress difficult or even impossible, and designed levels that proved challenging even for his friends. At the time, his wife's parents owned a record store with a small computer section. A salesman who saw the game suggested it had commercial potential. Imabayashi later ported the game to the NEC PC-8801, enhancing the graphics and expanding it to twenty levels. In 1982, he founded Thinking Rabbit in Takarazuka, Japan, and released the NEC PC-8801 version as the first commercial Sokoban game in December.

In 1983, the Japanese magazine PC Magazine published Sokoban Extra Edition as a type-in program with ten new puzzles, developed by Thinking Rabbit on request. In 1984, Thinking Rabbit released Sokoban 2, which included a puzzle editor. Throughout the 1980s, new titles appeared on various Japanese platforms, including home computers such as the MSX and PC-9801, and consoles like the Famicom, Sega SG-1000, Sega Mega Drive, and Game Boy. These releases were either developed by Thinking Rabbit or licensed to other companies. In 1987, Spectrum HoloByte in California licensed Sokoban from Japan's ASCII, adapted the MSX version for IBM PC, Apple II, and Commodore 64, added features for the U.S. market, and released it as Soko-Ban in early 1988. The official series continued in Japan during the 1990s with new titles for the Super Famicom, Windows, Macintosh, and PlayStation.

Around 2000, Thinking Rabbit became inactive but remained a legal entity. In 2001, the Japanese software company Falcon acquired the copyrights and trademarks for Sokoban and Thinking Rabbit, becoming the official developer and licensor. From 2004 to 2007, Falcon developed several titles for Japanese mobile phones. Between 2015 and 2018, Falcon developed five Sokoban titles for Windows and the smartphone game Sokoban Touch (2016), all of which were published by Falcon under the Thinking Rabbit brand. In 2018, Falcon developed three Sokoban titles for Japanese digital terrestrial television broadcasters.

Games

Since its debut in 1982, more than 40 official Sokoban games have been released on various platforms, primarily in Japan but also internationally. Most titles are standalone, with a few sequels. The core mechanic of pushing boxes to storage locations has remained consistent in nearly all official titles, with the following exceptions:

• One title includes stages with different core mechanics: features four themed stages with either strict move limits, boxes that float unless regularly touched or stored, a box that is a ghost, or boxes that, when stored, must complete an electrical circuit.
• Two titles have variant game modes: includes a mode where the player can use tools such as ropes, and offers a mode in which the player must push enemies into holes and push puppets onto magic circles.
• One title deviates from the warehouse keeper mechanic: is an action-puzzle game in which the player shoots orbs and fills holes with rocks.

The following table lists the titles in the Sokoban series.

Title	Release	Platform	Developer	Publisher	Region
	1982-1983	NEC PC-8801 NEC PC-6001mkII NEC PC-8001mkII Fujitsu FM-7 Sharp MZ-2000 Sharp X1	Thinking Rabbit	Thinking Rabbit	Japan
	1983	NEC PC-8801	Thinking Rabbit	Template:Ill	Japan
	1984	NEC PC-9801 NEC PC-8801 NEC PC-6001mkII NEC PC-8001mkII Fujitsu FM-7 Sharp X1 Template:Ill	Thinking Rabbit	Thinking Rabbit	Japan
	1984	MSX	ASCII	ASCII	Japan
	1984	MSX
	1985	Game Pocket Computer	Epoch	Epoch	Japan
	1985	SG-1000	Sega	Sega	Japan
	1986	Famicom Disk System	ASCII	ASCII	Japan
Soko-Ban	1988	IBM PC Commodore 64 Apple II	Spectrum HoloByte	Spectrum HoloByte	North America
	1989	NEC PC-9801 Sharp X68000 FM Towns	Thinking Rabbit	Thinking Rabbit	Japan
		MSX2	Template:Ill	Micro Cabin
BoxxleNA	1989	Game Boy	Pony Canyon	Pony CanyonJP FCINA	Japan, North America
	1991NA
Boxxle IINA	1990	Game Boy
	1992NA
	1990	Namco System 1	Namco	Namco	Japan
Shove It! The Warehouse GameNA	1990	Sega Genesis	Template:Ill	Template:IllJP DreamWorksNA	Japan, North America
	1990	Game Gear	Riverhill Soft	Riverhill Soft	Japan
BoxyboyNA	1990 1991	TurboGrafx-16	Media Rings	Media RingsJP NECNA	Japan, North America
	1991	NEC PC-9801	Thinking Rabbit	Thinking Rabbit	Japan
	1993	Super Famicom	Pack-In-Video	Pack-In-Video	Japan
	1995	Windows	Itochu	Itochu	Japan
	1996	Macintosh
	1996	PlayStation
	1997	PlayStation
	1997	Windows Macintosh
	1998	Windows	Itochu	Fujitsu Parex	Japan
	1998	Windows	Itochu	Itochu	Japan
	1998	PlayStation
	1998	Windows	Template:Ill	Unbalance	Japan
	1999	Super Famicom	Nintendo	Nintendo	Japan
	1999	Game Boy	Template:Ill	J Wing	Japan
	1999	PlayStation	Unbalance	Unbalance	Japan
	2000	Windows
	2000	Windows
	2004	EZweb	Falcon	Square Enix	Japan
(1/2/3)	2004	EZweb
	2004	i-mode	Falcon	Dwango	Japan
(1-1/1-2/1-3/2-1/2-2/2-3/3-1/3-2/3-3)	2004-2005	i-mode
	2007	i-mode	Konami	Konami	Japan
	2015	Windows	Falcon	Thinking Rabbit	Japan
	2015	Windows
	2016	Windows
	2016	Windows
Sokoban Touch	2016	Android iOS			Worldwide
	2018	Windows			Japan
	2018	Digital terrestrial television	Falcon	Chukyo Television	Japan
	2018	Digital terrestrial television		Miyagi Television
	2018	Digital terrestrial television		Nippon Television
JP The Sokoban	2019JP	Nintendo Switch PlayStation 4	Unbalance	Unbalance	Japan
	2021				Worldwide

Reception

The first Sokoban title became a bestseller in Japan, with over 25,000 copies sold by July 1984. Early releases for Japanese home computers, such as the NEC PC-9801 and Sharp X1, sold more than 100,000 copies combined. The MSX version, published by ASCII, sold over 400,000 copies and was considered a commercial success. The U.S. release, Soko-Ban, sold over 50,000 copies by mid-September 1988. By 2018, Chukyo Television Broadcasting reported that the series had sold over 4.1 million copies worldwide since its 1982 debut.

In 1990, Famicom Winning Guide recognized Sokoban as a staple puzzle game, noted for its difficulty, depth, and continued presence across multiple platforms. Reviewers often emphasized the game's addictive nature. Micomgames staff remarked that players would find it difficult to stop playing the first Sokoban. In 1988, Roy Wagner of Computer Gaming World suggested that anyone trying the US version, Soko-Ban, would likely remain absorbed for an extended period. The Computer Entertainer newsletter described the game as fascinating and almost impossible to stop playing. In its console reviews, Computer and Video Games magazine called Sokoban for Game Boy "an infuriatingly addictive little title" and compared its appeal to Tetris.

Commentators often highlighted one of three aspects of the game: its simplicity, the level of thought it required of players, or its challenging nature. Micomgames staff, however, emphasized both simplicity and the thinking required of players, describing the first Sokoban as simple yet requiring deep thought comparable to playing Go or Shogi. Family Computer magazine's All Catalog supplement described Sokoban for Game Boy as great due to the simplicity of its gameplay, and Computer and Video Games magazine staff described it as one of the Game Boy's "simple but effective puzzle games." Reviewers for the German magazine Happy Computer praised Soko-Ban as a brilliant logic puzzle that kept players thinking without pressure and recommended that players carefully observe a level before moving a box, and in Computer Gaming World, Wagner summarized it as "very playable and mentally challenging." In Game Player's magazine, Tom R. Halfhill reviewed Shove It! for the Sega Genesis, noting it was challenging and would require players to plan their moves carefully, and reviewing Boxxle for Game Boy, he stated that it required careful planning or plenty of trial and error (usually both). He later commented on Boxyboy for the TurboGrafx-16 that while the initial rooms were not difficult, players would eventually encounter one that "seems impossible."

The series faced criticism for its lack of variety. Tom R. Halfhill observed that all puzzles in Shove It! were essentially the same. He also noted that BoxxleTemplate:'s gameplay could become repetitive, with only the number and arrangement of crates and the room shape varying. In his review of Boxyboy, he found it "virtually identical" to Shove It! and Boxxle, concluding that these games required players to enjoy solving the same type of puzzle repeatedly.

Legacy

Numerous clones have been created, and the term "Sokoban," a registered trademark, has become genericized to describe the genre. Thousands of custom Sokoban puzzles, spanning various difficulty levels, are freely available online, along with software tools such as solvers and solution optimizers. The Sokoban puzzle principle, which involves pushing objects to the correct targets, is widely used in gaming. Despite advances in computer and console power during the 1980s and 1990s, many games continued to use tile- and grid-based movement, making object-pushing puzzles common. As a result, many older games featured puzzles similar to Sokoban. Titles such as Adventures of Lolo (1989), LIT (2009), and The Legend of Zelda series incorporated this principle in their gameplay. Resident Evil 2 (1998) also used this mechanic in a puzzle, requiring players to move statues to marked areas with attention to their orientation. Additionally, Sokoban-like games such as Sokomania 2 (2014) introduced new mechanics, including switches and conveyor belts.

Research

The computational problem of solving Sokoban puzzles has been studied using computational complexity theory, and is known to be NP-hard and PSPACE-complete. Solving non-trivial Sokoban puzzles is difficult for computers because of the high branching factor (many legal pushes at each turn) and the considerable search depth (many pushes needed to reach a solution). Even small puzzles can require lengthy solutions.

Sokoban puzzles provide a challenging testbed for developing and evaluating automated planning techniques. The first documented automated solver, Rolling Stone, was developed at the University of Alberta. It employed a conventional search algorithm enhanced with domain-specific techniques such as deadlock detection. A later solver, Festival, introduced the FESS search algorithm and became the first automatic system to solve all ninety puzzles in the widely used XSokoban test suite. Despite these advances, even the most sophisticated solvers cannot solve many complex puzzles that humans can solve with time and effort, using their ability to plan, recognize patterns, and reason about long-term consequences.

See also

• Logic puzzle
• Sliding puzzle
• Transport puzzle
• Motion planning

External links

• Official Sokoban site (in Japanese)
• The University of Alberta Sokoban page