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.
You should allow users to use the same gaijin account to redeem other offers too. For example, there is a war thunder and crossout offer which require two different gaijin accounts to redeem which seems ridiculous