Now that Xbox One has made itself known to the world, via Microsoft's unveil that was mostly about sports, TV, and sports TV, the real nitty gritty is being unveiled, but on the down low.
It wasn't mentioned during the presentation, but The Verge managed to get very telling bit of intel from Microsoft Xbox Live VP Marc Whitten. Which is how the new Xbox One will not be backwards compatible with existing Xbox 360 software.
Why? Whitten explains: "The system is based on a different core architecture, so back-compat doesn't really work from that perspective."
It is assumed that both full-sized, disc-based games and more bite-sized, downloadable games are both included. While this should come as no real shock, since it was tricky getting original Xbox games to play on the 360, Microsoft's current console also has a much larger library that more people have invested in.
Furthermore, it's understandable that something as big and complex as Halo 4 would not be able to run, but something far smaller and modest, like the Simpsons Arcade Game makes very little sense, since many XBLA games can be found on far less powered hardware with no fuss or muss.
It's also a shock to those who assumed that Microsoft would try to figure out a solution, after Sony flat out stated that the PS4 would not be compatible with the PS3, for largely the same reasons. Some viewed that backwards compatibility would be its ace in the hole.
Microsoft has stated that they will continue to produce the Xbox 360, which is a good thing. Because if the worst happens and your current 360 bites the dust, you'll have to get another one to migrate all your games and downloadable content. Because the One will not be able to handle any of it.