Here's all the free games you'll get on Xbox in December
Burnout Paradise, the critically acclaimed open-world racer from Criterion Games, will be available to play on Xbox One through backwards compatibility in December. The title is also part of the month's Games with Gold promotion, so you can download it for free.

The other Xbox 360 game that will also be available as part of Games with Gold is Housemarque's platformer Outland. From the Xbox One side, Outlast and Sleeping Dogs: Definitive Edition will be available.

If you haven't already, be sure to grab November's free Games with Gold titles, which are Super Dungeon Bros, Murdered: Soul Suspect, and Far Cry 3: Blood Dragon, as these games will be replaced in December.
Xbox One

Sleeping Dogs: Definitive Edition (Available throughout December)
Outlast (Available from December 16 until January 15)

Xbox 360

Burnout Paradise (Available from December 16 until December 31)
Outland (Available from December 1 until December 15)