Crusader Kings II, Magicka Collection, Sword of the Stars [Complete Collection], Sword of the Stars II: Lords of Winter & Victoria II, PC – £7.23
Registers on Steam.
To purchase digital games from Amazon US, use your UK Amazon account, and add a US billing address to your account. This address needs to be a valid US address, but nothing will be sent there, and you can access all your games through their website. Some card issuers may charge a fee.

Does buying from amazon US fuck with your steam account in anyway?
Any suggestions for an address?
Thanks