Every month, Xbox subscribers look forward to seeing what new Games with Gold games will be for free. It has been over two years since the Live with Gold program was announced, and to celebrate, Games with Gold will offer two new games on Xbox One every month starting in July 2015. A recent announcement about backwards compatibility of the Xbox One with the Xbox 360 has made Xbox Live with Gold subscribers optimistic as it could potentially double their free games. So far, there is a lot speculation as to what Xbox Live Games with Gold will be free games for September 2015, and these are the Xbox Live with Gold Free Games for September 2015.
According to Major Nelson, who is an excellent source for the free games with Microsoft's free games for their Games with Gold program, the free ones have been revealed for the month of September.
For the Xbox One, players have the option of getting The Deer God from September 1st to September 30th. According to the Steam Store, The Deer God is "a breathtaking 3D pixel art adventure that will challenge your religion and your platforming skills. It's a game about survival, reincarnation, and karma; all set in a breathtaking and unique 3D pixelized world".
A Definite crowd-pleaser for the Xbox One crowd is that Tomb Raider: Definitive Edition will be available as a free download from September 16th to October 15th. According to Amazon, this is the critically, acclaimed cinematic action-adventure, re-built specifically for next gen consoles. This will bring Lara Croft back to life in a lot of detail through many great adventures.
As for Xbox 360, they also get a free download with Battlestations Pacific, available from September 1st to the 15th. This is an action and real-time tactics game that expands on the Battlestations: Midway. In this game, the player goes beyond the World War II battle of Midway and head toward Okinawa for final victory.
From September 16th through the 30th, Xbox 360 users will be able to download Crysis 3. For those unfamiliar with Crysis, it is a first person shooter game series where the player runs around in a cool nanosuit fighting against aliens known as the Ceph. Crysis 3 is the final act of the series, and it takes place in post-apocalyptic New York City, as the player takes the Prophet to end the war with the Ceph once and for all.
I'll go ahead and answer the question that everyone is looking for as far as the free games for October 2015. The answer is sadly no answer, as the free Games with Gold are not usually announced until the month turns, and then there are usually only rumors. After doing several searches for October 2015 predictions Xbox Live Gold and similar keyword phrases, I could find no hint of any possible free game for October 2015. I suppose that I could probably start a rumor with a guess, but it really is anyone's guess. Maybe Xbox Live needs to have a Vote to Play like PlayStation.
I'll also answer the question about backwards compatibility, as it has been rumored that soon Xbox One users will have four free games to pick instead of the usual two. It hasn't been confirmed whether this will be the case. If it is, then that does change the playing field a bit.