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.
I did the first task and got my gems, but now the game is no longer listed in the games section. It can still be found via the search, however. Also, on the game page, the tasks are no longer shown, so what happened here? Does this happen often at GameHag, that a game and its tasks gets "deactivated"?