Microsoft has announced the Xbox Live Games with Gold lineup for September.
Headlining is Introversion's Prison Architect: Xbox One Edition, which is free to download for Xbox One Xbox Live Gold members throughout September.
Tuque Games' top-down shooter Livelock is available to download from 16th September to 15th October.
Elsewhere, on Xbox 360, Gold members can download Lego Star Wars 3: The Clone Wars from 1st September to 15th September. On 16th September, Sega Vintage Collection: Monster World is free until 30th September.
All the games in the Xbox Live Games with Gold promotion are backwards compatible on Xbox One.