From [WIkipedia](https://en.wikipedia.org/wiki/Dunnet_(video_game)) :
> The game starts out with the player standing at the end of a dirt road, but it turns to the surreal when players realize that they are actually walking around inside a Unix system, and teleporting themselves around the Arpanet.
Underground 1989 Czech computer game Indiana Jones in Wenceslas Square now online in English