This post was part of Wikipedia but seems to have vanished recently due to the Epic Games free games database being removed, a few services have opted to preserve the information and I figured meh why not so here it is, everything Games with Gold ever.
The original Xbox and 360 Games list can be found here, the Xbox One Games list here and videos where applicable for the releases here
Unlike Xbox 360 Games with Gold releases, Xbox One users must maintain their Xbox Live Gold memberships in order to keep access to downloaded titles. Should the user drop their membership, access is suspended until the membership is reinstated or the game is purchased outright.
Beginning in July 2015, Microsoft announced the expansion of the Games With Gold program to officially offer two games each month for the Xbox One, just like with the Xbox 360. Each game will be offered for a full month, with one game being available from the 1st of the month until the last day of the month and the second game being available from the 16th of the month until the 15th of the following month. This was a change from previous policy: when the program had begun including Xbox One games, it had started with two games, rotating them so that each month included one new game and one game that had been offered the month before.