Sokoban[a] is apuzzle video game series in which the player pushes boxes in a warehouse to get them onto storage locations. The game is viewed from atop-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 causing a deadlock, a situation where a box or the player becomes permanently trapped, making the puzzle unsolvable.
Hiroyuki Imabayashi created the firstSokoban 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. releaseSoko-Ban. In 2001, Falcon acquired theSokoban 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 highlighted the game's simplicity, its addictive and challenging nature, and the level of thought required.
Due to the creation of numerousclones, the name "Sokoban," a registered trademark, has becomegenericized to describe the genre. The series has inspired thousands of custom puzzles, as well as Sokoban-like games. Its puzzle concept of pushing boxes to clear a path or to move them to targets has also appeared in other video games. Furthermore, Sokoban puzzles have been studied in the fields of computational complexity and artificial intelligence.
Sokoban takes place in a warehouse viewed fromabove 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.[1]
The player can move one square at a time, either horizontally or vertically, onto an empty floor square.[2] 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.[3]
Sokoban requires players to plan several moves ahead and consider all possible outcomes.[4] Careless moves could leave a box permanently trapped against a wall or another box,[2] stuck in a dead end,[5] or permanently preventing access to boxes that still need to be moved.[6]: 38 Any such situation creates a deadlock that makes the puzzle unsolvable, regardless of future moves.[7]
In 1981, Hiroyuki Imabayashi created the firstSokoban game for theNEC PC-8001 as a hobby, featuring text-based graphics and five original levels. The core mechanic was inspired byHudson Soft's 1980 gameAldebaran #1 for theMZ-80K,[8] where players pushed luggage to block radiation.[9] 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.[10] Imabayashi later ported the game to theNEC PC-8801, enhancing the graphics and expanding it to twenty levels. In 1982, he foundedThinking Rabbit inTakarazuka,Japan, and released the NEC PC-8801 version as the first commercialSokoban game in December.[11][12]
In 1983, the Japanese magazinePC Magazine publishedSokoban Extra Edition as atype-in program with ten new puzzles, developed by Thinking Rabbit on request.[13] In 1984, Thinking Rabbit releasedSokoban 2, which included a puzzle editor.[14] Throughout the 1980s, new titles appeared on various Japanese platforms, includinghome computers such as theMSX andPC-9801, andconsoles like theFamicom,Sega SG-1000,Sega Mega Drive, andGame Boy.[15] These releases were either developed by Thinking Rabbit or by other companies under license agreements.[11] In 1987,Spectrum HoloByte in California licensedSokoban from Japan'sASCII, adapted the MSX version forIBM PC,Apple II, andCommodore 64, added features for the U.S. market, and released it asSoko-Ban in early 1988.[16][17] The official series[18] continued in Japan during the 1990s with new titles for theSuper Famicom,Windows,Macintosh, andPlayStation.[19]
Around 2000, Thinking Rabbit became inactive but remained a legal entity.[9] In 2001, the Japanese software company Falcon acquired the copyrights forSokoban,[20] becoming the official developer and licensor. From 2004 to 2007, Falcon developed several titles for Japanesemobile phones.[21][22] Between 2015 and 2018, Falcon developed fiveSokoban titles for Windows and thesmartphone gameSokoban Touch (2016), all of which were published by Falcon under the Thinking Rabbit brand.[19][23] In 2018, Falcon developed threeSokoban titles for Japanesedigital terrestrial television broadcasters.[24] In 2021, Unbalance both developed and published an official title,The Sokoban, for theNintendo Switch[25] andPlayStation 4.[26]
Since its debut in 1982, more than 40 officialSokoban games have been released on various platforms, primarily in Japan but also internationally. Most titles are standalone, with a few sequels.[19] The core mechanic of pushing boxes to storage locations has remained consistent in nearly all official titles,[3] with the following exceptions:
The following table lists the titles in theSokoban series.[19][15]
| Title | Release | Platform | Developer | Publisher | Region |
|---|---|---|---|---|---|
| Sokoban (倉庫番) | 1982-1983 | NEC PC-8801 NEC PC-6001mkII NEC PC-8001mkII Fujitsu FM-7 Sharp MZ-2000 Sharp X1 | Thinking Rabbit[31] | Thinking Rabbit | Japan |
| Sokoban Extra Edition (倉庫番[番外編]) | 1983 | NEC PC-8801 | Thinking Rabbit[13] | PC Magazine [ja] | Japan |
| Sokoban 2 (倉庫番2) | 1984 | NEC PC-9801 NEC PC-8801 NEC PC-6001mkII NEC PC-8001mkII Fujitsu FM-7 Sharp X1 MB-S1 [ja] | Thinking Rabbit[31] | Thinking Rabbit | Japan |
| Sokoban (倉庫番) (ROM pack) | 1984 | MSX | ASCII[32] | ASCII | Japan |
| Sokoban Toolkit (倉庫番ツールキット) (Tape pack) | 1984 | MSX | Seiji Nishikawa[33] | ||
| Sokoban (倉庫番) | 1985 | Game Pocket Computer | Epoch[34] | Epoch | Japan |
| Sokoban (倉庫番) | 1985 | SG-1000 | Sega[35] | Sega | Japan |
| Sokoban Special of Tears (涙の倉庫番スペシャル) | 1986 | Famicom Disk System | ASCII[36] | ASCII | Japan |
| Soko-Ban | 1988 | IBM PC Commodore 64 Apple II | Spectrum HoloByte[16] | Spectrum HoloByte | North America |
| Sokoban Perfect (倉庫番Perfect) | 1989 | NEC PC-9801 | Thinking Rabbit[37] | Thinking Rabbit | Japan |
| NEC PC-8801 | Thinking Rabbit[38] | ||||
| Sharp X68000 | Thinking Rabbit[39] | ||||
| Sharp X1 | Thinking Rabbit[40] | ||||
| FM Towns | Thinking Rabbit[41] | ||||
| MSX2 | Micro Cabin [ja][42] | Micro Cabin | |||
| Sokoban (倉庫番) BoxxleNA | 1989 | Game Boy | Atelier Double[43][44] | Pony CanyonJP FCINA | Japan, North America |
| 1991NA | |||||
| Sokoban 2 (倉庫番2) Boxxle IINA | 1990 | Game Boy | Atelier Double[45][46] | ||
| 1992NA | |||||
| Sokoban Deluxe (倉庫番Deluxe) | 1990 | Namco System 1 | Namco[47] | Namco | Japan |
| The Greatest Sokoban in History (史上最大の倉庫番) Shove It! The Warehouse GameNA | 1990 | Sega Genesis | NCS [ja][48][49] | Masaya [ja]JP DreamWorksNA | Japan, North America |
| Sokoban (倉庫番) | 1990 | Game Gear | Riverhill Soft[50] | Riverhill Soft | Japan |
| Sokoban World (倉庫番World) BoxyboyNA | 1990 1991 | TurboGrafx-16 | Media Rings[51][52] | Media RingsJP NECNA | Japan, North America |
| Sokoban Revenge (倉庫番Revenge) | 1991 | NEC PC-9801 | Thinking Rabbit[53] | Thinking Rabbit | Japan |
| Sokoban Revenge SX-68K (倉庫番リベンジ SX-68K) | 1993 | Sharp X68000 | Thinking Rabbit[54] | Sharp[54] | Japan |
| Super Sokoban (Super倉庫番) | 1993 | Super Famicom | Pack-In-Video[55] | Pack-In-Video | Japan |
| Sokoban for Windows (倉庫番 for Windows) | 1995 | Windows | Itochu[56] Outback[56] | Itochu | Japan |
| Sokoban for Macintosh (倉庫番 for Macintosh) | 1996 | Macintosh | Itochu[57] | ||
| Ultimate Sokoban (究極の倉庫番) | 1996 | PlayStation | Thinking Rabbit[58] | ||
| Sokoban Basic (倉庫番ベーシック) | 1997 | PlayStation | Outback[59] | ||
| Sokoban Selection (倉庫番セレクション) | 1997 | Windows | Itochu[60] Outback[60] | ||
| 1997 | Macintosh | Itochu[61] | |||
| Sokoban Special 102 (倉庫番スペシャル102) | 1998 | Windows | Itochu[62] Outback[62] | Fujitsu Parex | Japan |
| Ultimate Sokoban (究極の倉庫番) | 1998 | Windows | Itochu[63] Outback[64] | Itochu | Japan |
| Sokoban Basic 2 (倉庫番ベーシック2) | 1998 | PlayStation | Soft Office[65] Thinking Rabbit[65] | Unbalance | Japan |
| Power Sokoban (Power倉庫番) | 1999 | Super Famicom | Atelier Double[66][67] | Nintendo | Japan |
| Sokoban Legend: Land of Light and Darkness (倉庫番伝説 光と闇の国) | 1999 | Game Boy | J Wing [ja][29] | J Wing | Japan |
| Sokoban: Guide to Difficult Puzzles (倉庫番 難問指南) | 1999 | PlayStation | Thinking Rabbit[68] Three D[68] | Unbalance | Japan |
| 2000 | Windows | Unbalance[69] | |||
| Sokoban (倉庫番) | 2000 | Windows | Unbalance[70] | ||
| Sokoban First Step (倉庫番ファーストステップ) | 2004 | EZweb | Falcon[21] | Square Enix | Japan |
| Sokoban Perfect (倉庫番パーフェクト) (1/2/3) | 2004 | EZweb | |||
| Sokoban First Step (倉庫番ファーストステップ) | 2004 | i-mode | Falcon[22] | Dwango | Japan |
| Sokoban Perfect (倉庫番パーフェクト) (1-1/1-2/1-3/2-1/2-2/2-3/3-1/3-2/3-3) | 2004-2005 | i-mode | |||
| Konami Wai Wai Sokoban (コナミワイワイ倉庫番) | 2007 | i-mode | Konami[71] | Konami | Japan |
| Sokoban Perfect Plus A-side (倉庫番パーフェクト プラス A面) | 2015 | Windows | Falcon[72] | Thinking Rabbit | Japan |
| Sokoban Perfect Plus B-side (倉庫番パーフェクト プラス B面) | 2015 | Windows | |||
| Sokoban First Step Plus (倉庫番ファーストステップ プラス) | 2016 | Windows | Falcon[73] | ||
| Sokoban Revenge Reprint (倉庫番リベンジ 復刻版) | 2016 | Windows | Falcon[74] | ||
| Sokoban Touch | 2016 | Android iOS | Falcon[24] | Thinking Rabbit | Worldwide |
| Sokoban Smart (倉庫番スマート) | 2018 | Windows | Falcon[75] | Thinking Rabbit | Japan |
| Chukyo-kun no Sokoban (チュウキョ～くんの倉庫番) | 2018 | Digital terrestrial television | Falcon[24] | Chukyo Television | Japan |
| Dayon no Sokoban (だよんの倉庫番) | 2018 | Digital terrestrial television | Miyagi Television | ||
| Kumojiro no Sokoban (くもジローの倉庫番) | 2018 | Digital terrestrial television | Nippon Television | ||
| Minna no Sokoban (みんなの倉庫番)JP The Sokoban | 2019JP | Nintendo Switch PlayStation 4 | Unbalance[24] | Unbalance | Japan |
| 2021 | Worldwide |
The firstSokoban title became a bestseller in Japan, with over 25,000 copies sold by July 1984.[76][31][77] Early releases for Japanese home computers, such as the NEC PC-9801 and Sharp X1, sold more than 100,000 copies combined.[78] The MSX version, published by ASCII, sold over 400,000 copies and was considered a commercial success.[16][79] The U.S. release,Soko-Ban, sold over 50,000 copies by mid-September 1988.[16] By 2018, Chukyo Television Broadcasting reported that the series had sold over 4.1 million copies worldwide since its 1982 debut.[80]
Reviewers often emphasized the game's addictive nature. In 1983,Micomgames staff remarked that players would find it difficult to stop playingSokoban.[4] In 1988, Roy Wagner ofComputer Gaming World suggested that anyone trying the US version,Soko-Ban, would likely remain absorbed for an extended period.[81] TheComputer Entertainer newsletter described the game as fascinating and almost impossible to stop playing.[82] In its console reviews,Computer and Video Games magazine calledSokoban for Game Boy "an infuriatingly addictive little title" and compared its appeal toTetris.[83] In 1990,Famicom Winning Guide recognizedSokoban as a staple puzzle game, citing its difficulty, depth, and continued presence across multiple platforms.[84]
Commentators often highlighted one or more aspects of the game: its simplicity, the level of thought it required of players, or its challenging nature.Micomgames staff described the firstSokoban title as simple yet requiring deep thought comparable to playingGo orShogi.[4]Family Computer magazine'sAll Catalog supplement describedSokoban for Game Boy as great due to the simplicity of its gameplay,[28]: 199 andComputer and Video Games magazine staff described it as one of the Game Boy's "simple but effective puzzle games."[83] Writing forMSX Magazine [ja] in 1989, a reviewer citedSokoban as the representative example of a purely logic-based puzzle, distinguishing it from puzzles that incorporate action elements such as enemies or time pressure, and those involving elements of chance.[85] Reviewers for the German magazineHappy Computer praisedSoko-Ban as a brilliant logic puzzle that kept players thinking without pressure and recommended that players carefully observe a level before moving a box,[86] and inComputer Gaming World, Wagner summarized it as "very playable and mentally challenging."[81] InGame Player's magazine, Tom R. Halfhill reviewedShove It! for the Sega Genesis, noting it was challenging and would require players to plan their moves carefully,[87] and reviewingBoxxle for Game Boy, he stated that it required careful planning or plenty of trial and error (usually both).[88] He later commented onBoxyboy for the TurboGrafx-16 that while the initial rooms were not difficult, players would eventually encounter one that "seems impossible."[89]
The series faced occasional criticism for a lack of variety. Tom R. Halfhill wrote that the puzzles inShove It! were "essentially the same",[87] and noted that inBoxxle, variation was limited to crate count, placement, and room shape.[88] ReviewingBoxyboy, he described it as "virtually identical" to the others, concluding that all three games required players to enjoy solving the same type of puzzle repeatedly.[89]
Numerousclones have been created,[90] and the term "Sokoban," a registered trademark,[20] has becomegenericized to describe the genre.[91] Thousands of custom Sokoban puzzles, ranging in difficulty, are freely available online,[92][93] along with software tools such as solvers[94] and solution optimizers.[91] Puzzles resemblingSokoban, involving pushing boxes or similar obstacles to the correct targets, have been present in gaming,[95] particularly in 1980s and 1990s action-adventure games with grid-based movement.[96]The Legend of Zelda series and titles such asAdventures of Lolo (1989) andLIT (2009) incorporate Sokoban-style elements into their gameplay;[95] for example,The Legend of Zelda: A Link to the Past (1991) has a puzzle in which blocks must be arranged to clear a path to a treasure chest.[96]Resident Evil 2 (1998) includes a puzzle similar toSokoban in which two statues must be pushed onto corresponding marked floor areas, with the correct matching inferred.[96] Additionally, Sokoban-like games such asSokomania 2 (2014) introduce new mechanics, including switches and conveyor belts.[95]
The computational problem of solving Sokoban puzzles has been studied usingcomputational complexity theory, and is known to beNP-hard[97][98] andPSPACE-complete.[99][100] Solving non-trivial Sokoban puzzles is difficult for computers because of the highbranching factor (many legal pushes at each turn) and the considerablesearch depth (many pushes needed to reach a solution).[101][102] Even small puzzles can require lengthy solutions.[103]
Sokoban puzzles provide a challenging testbed for developing and evaluatingautomated planning techniques.[104] The first documented automated solver, Rolling Stone, was developed at theUniversity of Alberta. It employed a conventional search algorithm enhanced with domain-specific techniques such as deadlock detection.[6][105] A later solver, Festival, introduced the FESS search algorithm and became the first automatic system to solve the standard XSokobanbenchmark, a suite of ninety puzzles with a ten-minute per-puzzle time limit that had eluded a complete solution for more than twenty years.[106][107] Despite these advances, Sokoban puzzles that have been solved by humans are beyond the reach ofstate-of-the-art solvers.[93][108][109] Humans solve such instances by breaking down puzzles into subproblems,[6]: 40 recognizing patterns and exceptions, and drawing on learning from prior puzzles.[6]: 62
倉庫番シリーズ[Sokoban series]
