Ubisoft has been celebrating its 30th anniversary for 7 months now by offering one high profile game for free each month. The company previously announced that each game would be available for free for one month only, but it has now decided to give gamers a second chance to get all of the seven games.
Right now and till the end of December 18th, the following games can be obtained freely using nothing but a valid UPlay account.
• Prince of Persia: The Sands of Time
• Tom Clancy's Splinter Cell
• Rayman Origins
• The Crew
• Beyond Good and Evil
• Far Cry 3: Blood Dragon
• Assassin's Creed III
You don't need to download the games or play them right now. You only need to "buy" them for zero dollars while the promotion lasts, then they are users to own for good.
You can get the free games from UPlay Ubi30 page.