http://www.pcgamer.com/ubisoft-is-giving-away-watch-dogs-for-free/

Ubisoft announced earlier this month that it would mark the holidays by giving away a couple of oldies but goodies, first World in Conflict and then after that, Assassin's Creed 4: Black Flag. That plan has apparently changed somewhat, but in a good way, because it's added another game to the freebie festivities. 

From now (technically yesterday) until 5 am ET on December 23, the original Watch Dogs is free for the taking on Uplay. Hit up the "Happy Playdays" freebie page, log in if you need to, and the game will be automatically added to your library. And yes, it's permanent, as long as you get it before the offer expires.