If you are not in the EU you are not subject to its jurisdiction, but if you do business in the EU, you are. But they only have jurisdiction over your assets actually in the EU. So if you have an office or bank account in the EU, they can go after you. But if you don't, they can't do shit. What they could also do is go after the third parties facilitating the transaction, e.g. Steam, the payment processor, the payment network, etc.
It gets complicated by international treaties and other considerations, but that's the gist.