Update [8/16]: two of the games (For Honor and Epic Mickey 2) are now available, starting today!
Microsoft Store just announced their free Games with Gold for August and they're horror-ibly exciting. Some are available starting today, while others start later this month. Requires Xbox Live Gold subscription ($9.99 for 1-month, $25 for 3-months, or $60 for 12-months).
Titles are as follows (including one still available from July):
Death Squared (Xbox One) [7/16 to 8/15]
- Forza Horizon 2 Standard: 10th Anniversary Edition (Xbox One) [8/1 to 8/31]
Dead Space 3 (Xbox One and Xbox 360) [8/1 to 8/15]
- For Honor Standard Edition (Xbox One) [8/16 to 9/15]
- Disney Epic Mickey 2: The Power of Two (Xbox One and Xbox 360) [8/16 to 8/31]