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.
This were the tasks before this game got removed a few days ago:
Task 1: Reach level 4
Task 2: Reach level 5
Task 3: Reach level 6
They could be different when this game comes back. If it should come back.
It is a shame that they removed it. They were rather quickly earned points.