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.
Currently working on my quest playthrough. Should be achieveable with minimal effort over 1-2 months. Currently level 15, there is a massive strain on in game resources (gold) which can prolong quest completion.