If you own Amazon Prime, then you also happen to own Twitch Prime. It the program Twitch implement a couple years ago when Amazon acquired Twitch. It basically gives Prime members more value for their subscription. One of those perks is free monthly PC games similar to what Sony & Microsoft does.
Our snitch just told us that there will be six games up for grabs in May. Those games include High Hell, I Hope, Gone Home, Cluster Truck, Titan Souls, and Psychonauts. Just know you need to download the Twitch application to claim your games once you connect your Amazon account to Twitch.
April’s games are still up for download. You can try titles such as Tales From The Borderlands and Steamworld Dig 2.