I'm a China player. I can't use PayPal and credit card to pay where I am. I can't get the key back, but I need it. This game is very interesting. I need the key. What can you do?
I checked the information about paying with PayPal or credit card in China. Your payment should definitely work. You can contact Itch Support for clarification. You can also try to subscribe on my Patreon.
