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 I did everything correcty, all you have to do for your first task is to upgrade the Engine to lvl4. I'm pretty sure i completed that task but it keeps getting rejected, any help? screenshot: https://imgur.com/zys3WeH