Jigsaw is an interactive fiction (IF) game,[b][c] written by Graham Nelson in 1995.

[d] The game begins on New Year's Eve of 1999, with the player discovering a time machine enabling them to travel throughout the twentieth century (including voyage of the Titanic, discovery of penicillin, codebreaking of the enigma machine during World War II,[1] opening of the Suez Canal, and the recording of Abbey Road) to ensure history unfolds 'correctly' despite the activities of 'Black', a character who starts out as an antagonist but becomes the player's love interest.

[2] Jigsaw contains references to other interactive fiction games, including Trinity.

[e] Features of the game include attention to detail,[f] and a romantic relationship between the player's character and another central character whose gender is never revealed[2] (allowing the player to project the gender of their choice onto both).

Jigsaw has been described as "acclaimed,"[3] "epic...notable,"[1] and as "[perhaps] one of the most fun educational games in existence".