Those eligible need only select their platform (the same as the one they own Unity), and then choose between a selection of Ubisoft's latest titles like The Crew and Far Cry 4.
The troublesome launch of the latest Assassin's Creed led to Ubisoft retracting the Season Pass, and giving away the first planned add-on for free to all who own the core game. Those who also bought the Season Pass were given an additional choice of a free game:
● The Crew ● Far Cry 4 ● Watch Dogs ● Assassin's Creed Black Flag ● Rayman Legends ● Just Dance 2015
● Far Cry 4
● Watch Dogs
● Assassin's Creed Black Flag
● Rayman Legends
● Just Dance 2015
did a similar 'apology' following all the issues with SimCity. This offer from Ubisoft is available until March 15th, 2015. Check out the to claim your free game if you're eligible.