Sony has decided its PlayStation Network (PSN) Store isn't going to be the only place you can purchase digital PlayStation games. Utilizing a model similar to Valve's PC game marketplace Steam, the company will allow online retailers to launch their own storefronts for Playstation 3, Playstation 4, and Playstation Vita titles (although PS4 titles aren't listed right now). As spotted by Kotaku, Amazon launched its US PlayStation Network store today and is offering $5 PSN credit on digital orders -- credit which can be redeemed in its buy two get one free promotion starting at noon ET today. Digital PlayStation 4 games will launch alongside physical titles, making an all-digital game library a reality, but a Sony monopoly over pricing may have affected their overall success in the past. With Amazon's PlayStation Store, and other potential partnerships, Sony will let gamers shop around for the best game deals, just like they did with boxed copies.