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.
in my experience, ive found that games are inconsistent regarding the amount of effort needed to complete their tasks and the actual reward you earn from them. In your opinion, which games you think need a lot of grinding to complete all 3 tasks?