I would like to buy game https://watabou.itch.io/pixel-dungeon, but there is only PayPal option. When I try to pay, PayPal deny action because payment is in USD, but I should use RUB (as PP tell, I should use my local currency). Is there some options to avoid this issue?

The developer's account is configured to receive payments directly to their account. Generally we recommend all new developers to use our payout system which prevents this issue. The best way to get around it would be to contact the developer and see if they're willing to update their account settings.