EDIT: Promotion has expired now.
If you missed getting these games free (via Uplay)
you have another chance, as Ubisoft has extended the deadline to redeem them.
Watch Dogs: (18+ game)https://freetrial.ubisoft.com/promotions/watch-dogs-1/8/
Assassin's Creed 4: Black Flag (18+ game)https://freetrial.ubisoft.com/promotions/assassins-creed-black-flag/16/
World In Conflict: (16+ game)
Deadline to redeem these for free is the 23rd of December
but once they're in your Uplay library, you can keep them forever.
"Sometimes you gotta run before you can walk." - Tony Stark, Iron Man.