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 them 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' despite the activities of 'Black', a character who starts out as an antagonist but becomes the player's love interest.