I can't claim Shadow of Mordor on Prime Gaming because it says the game is not available in my region. How is that possible? I live in Thailand and I buy games from GOG all the time.

Probably the game is locked on your region. Try with a VPN to USA.

have you tried the VPN thing??

Are you having problems in getting the key from Prime Gaming or in redeeming the key for the game here on GOG?

As far as I know, Prime Gaming is not available in Thailand.
If you can't get the game from Prime Gaming, I suggest you to be very cautious about using a VPN in order to login to the service because circumvent region lock is likely against the terms of use and might have consequences on your Amazon Prime account.

Good day, i was wondering the same, but you can only claim the game after 5 october, its also saying in the prime video.

Check the date: the OP was a month ago for Shadow of Mordor not Shadow of War .. this forum combines both games (called Middle-earth series)