| Sokoban | |
|---|---|
 Sokoban official fan kit banner | |
| Genre | Puzzle |
| Developers | Thinking Rabbit ASCII Itochu Unbalance [ja] Falcon |
| Publishers | Thinking Rabbit ASCII Itochu Unbalance [ja] Other
|
| Creator | Hiroyuki Imabayashi |
| Platforms | Various
|
| First release | Sokoban 1982 |
| Latest release | The Sokoban 2021 |
Sokoban[a] is a series ofpuzzle video games in which the player pushes boxes around in awarehouse. The aim of the game is to get the boxes onto storage locations. Hiroyuki Imabayashi created the firstSokoban game in 1981 as a hobby, and the following year, his companyThinking Rabbit published an enhanced commercial version in Japan for theNEC PC-8801 computer. Over the years, new titles were released for various platforms, developed by Thinking Rabbit or other companies under license. The game became popular in Japan and internationally, and the official series has remained active, with its most recent title released in 2021.Sokoban has inspired unofficial versions, thousands of custom puzzles, similar games, and artificial intelligence research.
The game of 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 marked as 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]
PlayingSokoban requires thinking several steps ahead and visualizing all possible outcomes.[4] Players should think carefully and thoroughly before pushing a box to prevent it from being permanently trapped against a wall or other boxes,[5] or in a dead end.[6] These are deadlocks from which the puzzle cannot be solved, regardless of subsequent moves.[7]
In 1981, Hiroyuki Imabayashi created the firstSokoban game as a hobby for theNEC PC-8001 computer. The game used text-based graphics and featured five levels designed by him. For the core mechanic, he was inspired by a part of the gameplay inHudson Soft's 1980 action game, Aldebaran #1, for theMZ-80K,[8] where the player pushed luggage to act as a wall to prevent radiation.[9] Imabayashi conceptualized that in the warehouse, the boxes had to be organized, but they themselves also became obstacles in the process. He worked to design levels that provided a real challenge, and friends he invited to his home to play the game struggled to solve them. At that time, his wife's parents owned a record store with a small computer section. By chance, a salesman saw the game and suggested that it would sell. Imabayashi used aNEC PC-8801 computer in the store's computer section to port the game, enhancing the graphics and expanding the levels to twenty. In 1982, he founded his company,Thinking Rabbit, based inTakarazuka,Japan, and released this PC-8801 version as the first commercialSokoban game in December.[10][11]
In 1983, the Japanese magazinePC Magazine publishedSokoban Extra Edition as atype-in program featuring ten new puzzles. This game was developed by Thinking Rabbit under request.[12] In 1984, Thinking Rabbit publishedSokoban 2, featuring a puzzle editor.[13] Throughout the rest of the 1980s, new titles appeared on a variety of Japanese platforms, includinghome computers such as theMSX andPC-9801, andvideo game consoles such as theFamicom,Sega SG-1000,Sega Mega Drive, andGame Boy.[14] These releases were developed either by Thinking Rabbit or by other companies under license agreements.[15]
In 1987,Spectrum HoloByte, under license fromASCII, ported and adapted theMSX version ofSokoban toIBM PC,Apple II, andCommodore 64, adding features for the U.S. market. The game was released in the United States early in 1988 asSoko-Ban.[16][17]
In the 1990s in Japan, further titles followed for theSuper Famicom,Windows,Macintosh, andPlayStation.[18]
Around 2000, Thinking Rabbit became inactive but remained a legal entity.[9] In 2001, the Japanese software company Falcon acquired the copyright to the officialSokoban games and the trademarks forSokoban and Thinking Rabbit,[19] becoming the official developer and licensor of the series. From 2004 to 2007, Falcon developed several titles for Japanesemobile phones.[20][21] Starting in 2015, it also developed severalSokoban titles for Windows and later the smartphone gameSokoban Touch, all published under the Thinking Rabbit brand.[18]
Since its debut in 1982, over 40Sokoban titles have been released in total on various platforms, primarily in Japan but also in other regions. Most titles are independent, though a few are sequels. The core mechanic of pushing boxes to storage locations has remained consistent in almost all official titles, with a very few exceptions:
| Region | Title | Release | Platform | Developer | Publisher |
|---|---|---|---|---|---|
| Japan | Sokoban (倉庫番) | 1982-1983 | NEC PC-8801 NEC PC-6001mkII Sharp MZ-2000 Sharp X1 | Thinking Rabbit | Thinking Rabbit |
| Sokoban Extra Edition (倉庫番[番外編]) | 1983 | NEC PC-8801 | PC Magazine [ja] | ||
| Sokoban 2 (倉庫番2) | 1984 | NEC PC-8801 NEC PC-8001mkII Fujitsu FM-7 Sharp X1 | Thinking Rabbit | ||
| Sokoban ROM Pack (倉庫番 ROM Pack) | 1984 | MSX | ASCII | ASCII | |
| Sokoban Tape Pack (倉庫番 Tape Pack) | 1984 | MSX | |||
| Sokoban (倉庫番) | 1985 | Game Pocket Computer | Epoch | Epoch | |
| Sokoban (倉庫番) | 1985 | SG-1000 | Sega | Sega | |
| Sokoban Special of Tears (涙の倉庫番スペシャル) | 1986 | Famicom Disk System | ASCII | ASCII | |
| Sokoban Perfect (倉庫番Perfect) | 1989 | NEC PC-9801 Sharp X68000 FM Towns | Thinking Rabbit | Thinking Rabbit | |
| MSX2 | Microcabin [ja] | Microcabin | |||
| Sokoban (倉庫番) | 1989 | Game Boy | Pony Canyon | Pony Canyon | |
| Sokoban 2 (倉庫番2) | 1990 | Game Boy | |||
| Sokoban Deluxe (倉庫番Deluxe) | 1990 | Namco System 1 | Namco | Namco | |
| The Greatest Sokoban in History (史上最大の倉庫番) | 1990 | Sega Genesis | NCS [ja][26] | Masaya [ja] | |
| Sokoban (倉庫番) | 1990 | Game Gear | Riverhill Soft | Riverhill Soft | |
| Sokoban World (倉庫番World) | 1990 | TurboGrafx-16 | Media Rings | Media Rings | |
| Sokoban Revenge (倉庫番Revenge) | 1991 | NEC PC-9801 | Thinking Rabbit | Thinking Rabbit | |
| Super Sokoban (Super倉庫番) | 1993 | Super Famicom | Pack-In-Video | Pack-In-Video | |
| Sokoban for Windows (倉庫番 for Windows) | 1995 | Windows | Itochu | Itochu | |
| Sokoban for Macintosh (倉庫番 for Macintosh) | 1996 | Macintosh | |||
| Ultimate Sokoban (究極の倉庫番) | 1996 | PlayStation | |||
| Sokoban Basic (倉庫番ベーシック) | 1997 | PlayStation | |||
| Sokoban Selection (倉庫番セレクション) | 1997 | Windows Macintosh | |||
| Sokoban Special 102 (倉庫番スペシャル102) | 1998 | Windows | Fujitsu Parex | ||
| Ultimate Sokoban (究極の倉庫番) | 1998 | Windows | Itochu | ||
| Sokoban Basic 2 (倉庫番ベーシック2) | 1998 | PlayStation | |||
| Sokoban Basic (倉庫番ベーシック) | 1998 | Windows | Unbalance [ja] | Unbalance | |
| Power Sokoban (Power倉庫番) | 1999 | Super Famicom | Nintendo | Nintendo | |
| Sokoban: Guide to Difficult Puzzles (倉庫番 難問指南) | 1999 | PlayStation | Unbalance | Unbalance | |
| Sokoban Legend: Land of Light and Darkness (倉庫番伝説 光と闇の国) | 1999 | Game Boy | J Wing | J Wing [ja] | |
| Sokoban (倉庫番) | 2000 | Windows | Unbalance | Unbalance | |
| Sokoban: Guide to Difficult Puzzles (倉庫番 難問指南) | 2000 | Windows | |||
| Sokoban First Step (倉庫番ファーストステップ) | 2004 | EZweb i-mode | Falcon[20][21] | Square Enix Dwango | |
| Sokoban Perfect (倉庫番パーフェクト) (1/2/3) | 2004 | EZweb | Square Enix | ||
| 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 | Dwango | ||
| Konami Wai Wai Sokoban (コナミワイワイ倉庫番) | 2007 | i-mode | Konami[27] | Konami | |
| Sokoban Perfect Plus A-side (倉庫番パーフェクト プラス A面) | 2015 | Windows | Falcon | Thinking Rabbit | |
| 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 | |||
| Sokoban Revenge Reprint (倉庫番リベンジ 復刻版) | 2016 | Windows | |||
| Sokoban Smart (倉庫番スマート) | 2018 | Windows | |||
| North America | Soko-Ban | 1988 | IBM PC Commodore 64 Apple II | Spectrum HoloByte[16] | Spectrum HoloByte |
| Shove It! The Warehouse Game | 1990 | Sega Genesis | NCS [ja] | DreamWorks | |
| Boxyboy | 1990 | TurboGrafx-16 | Media Rings | NEC | |
| Boxxle | 1990 | Game Boy | Pony Canyon | FCI | |
| Boxxle II | 1992 | Game Boy | |||
| Worldwide | Sokoban Touch | 2016 | Android iOS | Falcon | Thinking Rabbit |
| The Sokoban | 2021 | Nintendo Switch PlayStation 4 | Unbalance [ja] | Unbalance |
The firstSokoban title was a commercial success in Japan, selling over 25,000 copies by July 1984.[28][29][30]
| Publication | Score |
|---|---|
| Family Computer [ja] | 13.45/25 (FD・Sokoban Special of Tears (涙の倉庫番スペシャル)[23] 18.78/30 (GB・Sokoban (倉庫番)[31] 17.65/30 (GB・Sokoban 2 (倉庫番2)[32] |
| Computer and Video Games | 88% (GB・Sokoban (倉庫番)[33] |
| Happy Computer | 87/100 (PC・Soko-Ban)[34] |
| Dragon | 4.5/5 (PC・Soko-Ban)[35] |
| BEEP! Mega Drive [ja] | 25/40 (SG・The Greatest Sokoban in History (史上最大の倉庫番)[26] |
In a 1990 issue ofFamicom Winning Book, the magazine described the series as "one of the few early computer games that continues to be discussed today, noted for its difficulty and depth" (translated from Japanese). It also stated that the game "has established a firm position as a staple of puzzle games, and has been ported to numerous platforms, including various [Japanese personal computer platforms], where it continues to be published" (translated from Japanese).[36]
A December 1983 issue ofMICOMGAMES wrote that the puzzle's concept is simple but requires thinking comparable toGo orShogi, and that "once you start playing, it is hard to stop" (translated from Japanese). The magazine rated the game's originality 90 out of 100.[37]
In the JapaneseFamily Computer magazine'sAll Catalog supplement,Sokoban Special of Tears was called "a pioneering puzzle game" (translated from Japanese) and received 13.45 out of 25 points.[23]
In 1988, in the May issue ofComputer Gaming World, Roy Wagner reviewedSoko-Ban (for the IBM PC and Commodore 64). He emphasized the game's addictive quality by suggesting that anyone trying it would likely remain absorbed for a prolonged period, concluding thatSoko-Ban was "very playable and mentally challenging."[38] The IBM PC version was also reviewed by other publications that year; the German magazineHappy Computer, in its January issue, gave it a rating of 87 out of 100, calling it "a brilliant, relaxed logic puzzle that keeps you thinking without pressure" (translated from German),[34] andDragon magazine's mini-reviews, by Hartley, Patricia, and Kirk Lesser, considered it their favorite combination of an arcade and strategy game, rating it with 4.5 out of five stars.[35] Separately, theComputer Entertainer newsletter recommended the Apple II version, indicating that playing it was fascinating and almost impossible to stop, receiving 3.5 out of four stars for gameplay and entertainment, with the same rating for graphics.[39]
In the June 1990 issue ofGame Player's magazine, Tom R. Halfhill reviewedBoxxle, stating that it also required careful planning or plenty of trial and error (usually both). He noted that the game's gameplay could become repetitive because the only variations in the 108 screens were the number and arrangement of crates and the shape of the rooms.[40]
Computer and Video Games magazine ratedSokoban (倉庫番) for Game Boy 88% overall, indicating it as one of the "simple but effective puzzle games." It compared the game's addictiveness withTetris, stating the game "is an infuriatingly addictive little title; not quite on a par withTetris, but not far off."[33] In the JapaneseFamily Computer magazine'sAll Catalog supplement,Sokoban (倉庫番) for Game Boy was described as great because of its simple gameplay, receiving 18.78 out of 30 points.[31]Sokoban 2 (倉庫番2) was also noted as significantly more difficult and received 17.65 out of 30 points.[32]
In the March 1990 issue of the Japanese magazineBEEP! Mega Drive,The Greatest Sokoban in History (史上最大の倉庫番) received a total score of 25 out of 40. Three of the four reviewers recommended it for puzzle enthusiasts. One reviewer questioned the release ofSokoban on the Mega Drive, wondering whether people would buy the console specifically to play a puzzle game; another appreciated the user-friendly gameplay but noted its dated feel; and one commented that he did not find the game's main selling points—enhanced art and its 250 levels that could take months to complete—particularly appealing.[26]
In the June 1990 issue ofGame Player's magazine, Tom R. Halfhill reviewedShove It! for Sega Genesis, noting it was a challenging game that required players to plan their moves carefully and that its unhurried pace was a refreshing respite from frenzied action games. However, all 160 puzzles were essentially the same.[41] In the December 1990 issue of the same magazine, Halfhill reviewedBoxyboy, highlighting its logical, untimed puzzles and describing it as a welcome change from typical action games, noting that it was "virtually identical" toShove It! andBoxxle.[42]
EarlySokoban titles released for numerous Japanese home computer systems such as theNEC PC-9801 andSharp X1 were a hit, selling over 100,000 copies in total.[43]
Spectrum Holobyte acknowledged that before 1988, over 400,000 copies of the game were sold in Japan, considering it a commercial success. This figure referred to the JapaneseSokoban title forMSX published byASCII in 1984. The U.S.Soko-Ban title, sold over 50,000 units by mid-September of 1988.[44][16]
The name "Sokoban" is a registered trademark for video game titles. However, the core mechanic of pushing boxes to storage locations on a grid is not protected by intellectual property rights. This has enabled others to create many unofficial versions.[45] Consequently, the term "Sokoban," which refers to the officialSokoban games, has become genericized and is also used to describe box-pushing puzzle games that adopt the same core mechanic.[46]
The active fan community has created thousands of custom puzzles spanning a wide range of difficulty,[47] as well as software tools, including puzzle editors, solvers,[48] and solution optimizers.[46]
Several independently developed games are based onSokoban, introducing new mechanics or objectives. One example isSokomania 2: Cool Job, which featured switches, conveyor belts, and boxes that continued moving after being pushed once.[49]
Sokoban has been studied using the theory ofcomputational complexity. The computational problem of solvingSokoban puzzles was first shown to beNP-hard.[50][51] Further work proved it is alsoPSPACE-complete.[52][53] Solving non-trivialSokoban 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).[54][55] Even small puzzles can require lengthy solutions.[56]
TheSokoban game provides a challenging testbed for developing and evaluatingplanning techniques.[57] 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.[58][59] 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.[60][61] 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.[62][63][64]
