While Microsoft has been vocal about how effective the Xbox Series X's backwards compatibility is, Sony has complicated its messaging a bit.

At first it simply promised that "the top 100 PS4 titles" would be playable at launch, but later added that it believed "the overwhelming majority of the 4,000+ PS4 titles" would be playable on the PS5. Sony revealed that nearly every game the company has tested runs flawlessly.

In an interview with The Washington Post, PlayStation boss Jim Ryan revealed that "99%" of the thousands of games tested for backward compatibility will play on the new hardware. This is a huge relief, given rumors that Sony will allow people to try out their favorite games on the console, rather than manually whitelisting compatible games.

However, while this is definitely good news, there are some potential holes. First, the backwards compatibility only applies to one generation. This means that PS1, PS2, and PS3 compatibility is not promised, but some titles may be streamed through Sony's PlayStation Now service.

Besides, the vexing issue of ownership is also an unknown. For the regular PS5, the backward compatibility mechanism is clear: simply insert the PS4 disc into the drive and start playing, but what about the lower-priced discless versions? Will PS4 game owners have to pay for the digital versions, or will Sony provide a mechanism to transfer ownership rights? Will Sony provide a mechanism for transferring ownership? In particular, Microsoft has been quite bullish on its Xbox Smart Delivery system, promising a solution for disc owners and non-disc owners to play games across console generations.

Indeed, backward compatibility for the Xbox Series X is nearly flawless, supporting not only Xbox One games, but also 360 and original Xbox titles, many of which are available for free through the excellent Games Pass service. I say "nearly perfect" because there is no way to play the handful of Xbox One titles that require the Kinect sensor. However, given that the total number of Kinect-supported games was less than 50, this is not a huge loss.

Of course, in the big picture, backward compatibility is a niche fervor and not that important to most people. If it were, the Wii U would have done much better. With that in mind, it is quite gratifying that both Microsoft and Sony are spending quite a bit of time making sure that backward compatibility works well in time for the November release dates of both consoles.