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.
Self explanatory of what I am saying, Milsim means Military Simulators I am talking about the great ones not the super bad ones like vikinglaws or some border game