Klotski 华容道
Klotski (from Polish klocki—wooden blocks) is a sliding block puzzle thought to have originated in the early 20th century. The name may refer to a specific layout of ten blocks, or in a more global sense to refer to a whole group of similar sliding-block puzzles where the aim is to move a specific block to some predefined location.
Rules
Like other sliding-block puzzles, several different-sized block pieces are placed inside a box, which is generally in 4×5 size. Among the blocks, there is a special one (usually the largest) which must be moved to a special area designated by the game board. The player is not allowed to remove blocks, and may only slide blocks horizontally and vertically. Common goals are to solve the puzzle with a minimum number of moves or in a minimum amount of time.
Naming
The earliest known reference of the name Klotski originates from the computer version for Windows 3.1 by ZH Computing in 1991, which was also included in Microsoft Windows Entertainment Pack. The sliding puzzle had already been trademarked and sold under different names for decades, including Psychoteaze[1] Square Root,[2] Intreeg,[3] and Ego Buster. There was no known widely used name for the category of sliding puzzles described before Klotski appeared.