I’ll keep this short and sweet. Ubisoft is having a holiday promotion where you can get three free titles. For PC: Assassin’s Creed Black Flag, Watch Dogs, and World in Conflict.
To get the games you will need to register for a free Ubisoft account, then claim the titles and add them to your game library. To actually play the games you will need to download and install the Play client.
Once the client is installed, you will find the games in your library from where you can download and install them.
Get the bundle here.