Play games
Choose the game that interests you and play itfor free.
Complete the quests
Every game has some quests for which you will receive Soul Gems.
Receive rewards
You can exchange your Soul Gems for Steam Wallet top-ups, game keys, CS:GO Skins and other rewards.
I think steam has gone crazy with this quarantine we have another 5 steam games today.
you know what to do just add them to your account and keep them forever !
1) The Deed
https://store.steampowered.com/app/420740/The_Deed/
2) Martian Law
https://store.steampowered.com/app/1135570/Martian_Law/
3) Barro
https://store.steampowered.com/app/618140/Barro/
4) UNI
https://store.steampowered.com/app/1011300/UNI/
5) HELLION
https://store.steampowered.com/app/588210/HELLION/
-World war z is free on epic store, it's a really good game guess it's worth mentioning.
https://www.epicgames.com/store/en-US/product/world-war-z/home