Microsoft has been more ambitious with backward compatibility. The $499 Xbox Series X and $299 Series S, which launched Tuesday, Nov. 10, play original Xbox, Xbox 360 and Xbox One games. That's four generations of games, stretching back to the first console's 2001 launch. 

But it doesn't include literally everything. Microsoft has a comprehensive list of the games that play on its new consoles: 568 games from the Xbox 360 and only 39 games from the original Xbox library are currently backward compatible. And titles that require its defunct Kinect motion sensor won't work at all.

Old games get a visual boost on the Series X and Series S, by way of high dynamic range graphics. 

"After 500K+ hours of testing, we're are excited to share that all Xbox, Xbox 360 and Xbox One games playable on Xbox One today, except for the handful that require Kinect, will be available -- and look and play better -- on Xbox Series X|Sat launch," Jason Ronald, Xbox director of program management, tweeted on Oct. 28.