In a new exclusive feature to the Playstation 4 and Playstation 3 games can join a friend on Far Cry 4 and cooperatively even if their friends don’t own the game. Gamers without Far Cry 4 will have to download a separate client that includes all of the game’s assets besides the single-player missions.
When your playing with your friends the gameplay will be more difficulty and will give you a good challenge. Far Cry 4 will release on November 18th for PlayStation 4, PlayStation 3, Xbox One, Xbox 360, and PC. Source Eurogamer