You won't get soul gems just for playing, there are tasks you have to complete. It tells you what they are when you click on them and then you have to submit screenshots of properly completed tasks. When the screenshots get reviewed you can get XP and soul gems for them. There is nicely written tutorial about all this stuff in the "from users" section on the forums.
in 3 steps
Choose the game that interests you and play itfor free.
Every game has some quests for which you will receive Soul Gems.
You can exchange your Soul Gems for Steam Wallet top-ups, game keys, CS:GO Skins and other rewards.
You know that on Gamehag you can get real rewards for free, right? Join us, complete walkthrough and get your chest!
Hey, I was wondering what the point of the games featured on here are for? Do they have soul gems available for just playing them or are there in game tasks to accomplish? I haven't seen much clarification on that