July's Games With Gold offering is a solid one, with recently released Nordic-fantasy RPG The Banner Saga 2 headlining the offering from Microsoft on Xbox One (it's available July 1-31). Tumblestone will also be free (from July 16 through to August 15) on the console. Meanwhile on Xbox 360 (and on Xbox One thanks to backwards compatibility) Rainbow Six: Vegas 2 is available for free in the first half of the month (July 1-15) and Tron: Evolution follows thereafter (July 16-31).
