So what’s the deal? Why is Fallout 3 not available on the PS4? It turns out that backwards compatibility is the key here. According to Bethesda’s Pete Hines, “well for one thing ps4 doesn’t support or plan to support backwards compat.” Hines’ statement echoes what Sony said a few months ago.
When asked if Sony would eventually support backwards compatibility like the Xbox One, Sony’s response at that time was that there are no plans to do so. Because of this, it looks like Fallout 3 will not be arriving on the PS4. It should be noted that Fallout 3’s release on the Xbox One is basically the Xbox 360 version of the game.
This is versus a remastered or HD remake version of the game, in which Bethesda could then make a version of the PS4. However since Sony does not plan to support older titles, there is really nothing Bethesda can do about it.