Not sure if this has been mentioned yet, but there's a bunch of free games on Twitch Prime (Twitch for Amazon Prime customers)
"In March, Twitch Prime subscribers will get Superhot, Shadow Tactics, Tales from Candlekeep, Oxenfree and Mr. Shifty. Next month, Free Games with Prime will offer Tales from the Borderlands, SteamWorld Dig 2, Kingsway, Tokyo 42 and Dubwars." https://www.polygon.com/2018/3/13/17117190/twitch-prime-free-games-pc
You'll have to download the games through the Twitch.tv client; it appears they won't expire.
These games get added to amazon account? As direct downloads (such as Humble Bundle)? Or Some other way?