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 the game is losing a lot of players and its too bad cause the game is really good it's a survival game and you fight zombies or other players and you can also form teams with other players