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.
R0PRE-NNIGQ-VHPD# ;
Just replace the # with the missing letter.
The game is in early access, but it's a promising one.
If someone takes the key right before you, but you still really want it, there's a giveaway for this game for now. It googles easily, I won't post the direct link in order to avoid the possible breaking the rules. Good luck! :)