Microsoft just revealed the following games will be free during October 2018 to Xbox Live Gold members:
Xbox One:
Overcooked – free Oct 1 – Oct 31
Victor Vran – free Oct 16 – Nov 15
Xbox One:
Stuntman Ignition– free Oct 1 – Oct 15
Hitman Blood Money – free Oct 16 – Oct 31
Also, side note, Forza Horizon 4 and Wolfenstein: The New Order will be coming to GamePass in October.