is it possible to sell a game i have in inventory for coins

Also when do i get the reward i got the game this morning and it says waiting

Is being prepared for dispatch*

It takes between 10mins and 72hrs to get a game. And you should have an option to sell the game thats in your inventory for Soul Gema

In addition to the above comment: According to the terms, Gamehag has 30 days to deliver your reward, so expect it to take longer than 72 hours.