On Xbox One, Xbox Live Gold members can download Earthlock: Festival of Magic ($29.99 ERP) for free during the month of September. Assassins Creed Chronicles: China ($9.99 ERP) will be available as a free download from September 16th to October 15th.
On Xbox 360, starting Thursday, September 1st, Forza Horizon ($19.99 ERP) will be free for Xbox Live Gold members through September 15th. Then on September 16th, Xbox Live Gold Members can download Mirrors Edge ($14.99 ERP) for free through September 30th.