Earlier today it was made public that Amazon had locked certain games behind a $99 a year paywall called their Prime membership. Apparently, the PS4 versions of GTA 5, Rainbow Six Siege and Assassin's Creed Syndicate, along with the PS4 and Xbox One versions of FIFA 16, Far Cry Primal, Battlefield Hardline were exclusively available to Prime members.
This was only the case with games sold by Amazon itself – not by third-party retailers.
It appears as though the negative reaction the exclusivity had Amazon changing their minds almost as immediately as the news went public. Amazon has rescinded their initiative to restrict the availability of specific games to Amazon buyers.
All of the previously mentioned games are once again available to both Prime and non-Prime members.