Depth Hunter, Derrick the Deathfin, Dungeon Hearts, Garshasp: Temple of the Dragon, Guns of Icarus Online, Mutant Mudds, SpaceChem, Ticket to Ride, Tower Wars & Toy Soldiers, PC – £6.36
Dungeon Hearts, Guns of Icarus Online, SpaceChem, Ticket to Ride, Tower Wars & Toy Soldiers register 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.

It says [download] next to Ticket To Ride & Tower Wars, so I’m guessing not redeemable on Steam after all?
Sorry Toy Soldiers not Tower Wars