Hang on, they sent you a demand for legal fees, by email, addressed to Mr Persson, (sic). Sure. take the game down to be on the safe side but otherwise ignore completely, you should not have sent any message in reply.
Or, if you have money to burn. you could sign the letter, send the payment, in cash, all smeared in your best beer shits.
Or if you have nothing more pressing to do, you could make it your lifes mission to be a lot more trouble than you're worth, maybe get yourself a rocket car and a solid gold house out of the whole thing.