Note: This article is coming from Khaljiit. Her tips for contacting game devs for copies of the game first appeared in Twitch reddit and these tips and tools are really good and priceless information!
Thanks for Khaljiit for allowing me to post this on here also. She also runs a community for streamers and game devs to get in touch with eachother that you could be interested.
And its actually a really simple process, just keep in mind a few things before you start asking for games.
1) You should have a email set up just for this purpose, and it should be on display on your twitter/twitch to verify that you are who you say you are in your email.
Note: If they have a Press Kit page, there might be a little form to simply request the game right on there, no email needed just give them your twitch name and a bit of info!
4) Write your email! Nothing complicated but you should include a few basic things: A greeting, your name and twitch name, on what system do you want the game, why you want to stream the game, your twitch and twitter links, and a little thank you for looking at your email!
5) When you stream, post on twitter, tag the game studio, the person who gave you the game, they will show up sometimes and help, plus they like knowing the game actually went toward a stream.
Honestly, thats it. I started doing this when I had ~100 twitch followers and I got a bunch of games to stream, some people said no that I was too small, but after I grew a little I emailed them back asking to reconsider, and they said yes and were happy that I got back in contact!
There are also just some websites to request keys directly which ive had some luck with!
Let me know if you want any help 😀 Sometimes, being part of a community helps or if its a co op game having someone to play with already might make the difference.