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.
there is a plethora of content, I play on ps4 and have been for a long time a new portion of the game came out not to recent but pretty close if your give it a try you won't regret it