send one more communication to them via the same way you've received a response in the past...
Tell them, "I've made several unsuccessful efforts to contact you regarding picking up this game. This will be my last correspondence before I have to assume you will not be retrieving it and the deal is dead. And since there's been no communication from you, and I have no info or means to refund your payment minus deposit (assuming that's actually the case), I will not be doing so. You have one week from the timestamp of this message to reply before I have to move forward without you.
If no response within one week after that, the game is yours to do as you please with. You did your best.