Soko-Ban

Sokoban can be studied using the theory of computational complexity. The problem of solving Sokoban puzzles has been proven to be NP-hard. 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.

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.

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, mobile phones, graphic calculators, and Canon PowerShot digital cameras. 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.