Published: 2022 May 22
The first commercial Sokoban game was created in 1982 for PC-8801 and was distributed in a cassette tape format in 1982.
The source code of the game was also included in the 1987 book "THE 倉庫番" (pages 117-122).
This game has 20 levels, but only the first 10 levels used the main Sokoban mechanics. Levels 11 to 20 adopted a secret mechanic: the player can break some predefined walls by pressing them from a certain side, leaving a free space in their wake.
The breakable walls did not differ visually from ordinary walls, but breaking them is essential to solving the level.
Curiosity: The cassette tape for this game is physically blank on side B, but reading the content reveals the entire game is present on both sides!