Far Cry Primal's map is largely based on that of 2014's Far Cry 4, down to the same road and river layouts.
It's something of a surprise, since the Stone Age valley of Oros is set in Central Europe and Far Cry 4 is supposed to be set in the Himalayas.
Developer Ubisoft never mentioned Primal would be based on Far Cry 4's map prior to the game being released, and the discovery of this fact has left some fans surprised.
Far Cry 3: Blood Dragon used portions of the main Far Cry 3 map, although it was sold as a downloadable spin-off, as suggested by the inclusion of Far Cry 3 in its title.
Primal, on the other hand, is a full-priced retail release.
The various similarities in each game's map have been highlighted by GamePressure in the two images below:
To be fair to Ubisoft, Primal has obviously done a pretty decent job at the conversion - the game has been out over a week before the similarity was widely noticed.
Nevertheless, terrain is similar, and even river crossings are located in the same places - with Far Cry 4's bridges replaced by fords in Primal.
We've contacted Ubisoft to find out more.