duffymoon: Even for other EU countries using the Euro? That would be questionable given they could be seen as a charge on trading with some parts of the EU rather than others. I can see they might have (very small) costs if there were different currencies though.
Yes, definitely. It's the condition of the card. I don't have any basic fee per year, and I don't pay much by credit card, so overall it's not much. But now that I think about it, you're right. It is kind of discriminating.
I should try paypal with € on GOG. That may be a way to circumvent the fee. I remember from the past that paypal uses an unfair conversion rate (about 1.5% unfair) so that it almost exactly comes out the same but with the € prices on GOG it might work without a fee.
Anyway the irony is that GOG converts everything to Polish Zloty and Euro when making their annual financial statements. So a lot of conversions going on back and forth behind the scenes.