Jigsaw (video game)

Jigsaw is an interactive fiction (IF) game, written by Graham Nelson in 1995.
The game begins on New Year's Eve of 1999, with the player discovering a time machine enabling him or her to travel throughout the twentieth century (including voyage of "The Titanic", discovery of penicillin, codebreaking of the enigma machine during World War II, opening of the Suez Canal, and the recording of "Abbey Road") to ensure history unfolds 'correctly'.
"Jigsaw" contains references to other interactive fiction games, including "Trinity". Features of the game include attention to detail, and a romantic relationship between the player's character and another central character whose gender is never revealed (allowing the player to project the gender of their choice onto both).
"Jigsaw" has been described as "acclaimed," "epic...notable," and as "[perhaps] one of the most fun educational games in existence". The gameplay is challenging.