See too "Microsoft's two-in-one package: Xbox Ultimate Game Pass"
With Marooners and The Golf Club 2 on the Xbox One side, the PGA Tour will be a free game this month. On the Xbox 360 side, Earth Defense Force: Insect Armageddon and Comic Jumper are referred to as May games. Xbox 360 games with backward compatibility can also be played on Xbox One.
Marooners (1-3 May)
Golf Club 2 with PGA Tour (May 16 to June 15)
Xbox 360 (compatible with Xbox One)
Earth Defense Force: Insect Armageddon (May 1 to 15)
Comic Jumper (May 16-31)