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.
World of Tanks posts sceenshots of different tanks in HD graphics and I imagine, "Oh man, I wish if we could have photo-realistic textures for our tanks". It's been long time graphics had been updated. Now we have ships. Ships would be looked nice in new texture.