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.
Many apps in the contracts section have no description of what task you must complete. The only thing it says is “AdGateRewards Only”. If anyone knows what this means please share.