For months, Sony has been fairly cagey about the scope of the PS5's backward compatibility, but things appear to be moving in the right direction. First, the company announced that "the top 100 PS4 titles" would work on the PS5 at launch, but then added that it believes "the overwhelming majority of the more than 4,000 PS4 titles will be playable on the PS5."

When the company released the list of 10 incompatible titles, many were relieved, except for a few hardcore fans of We Sing. Now, however, Ubisoft has cast doubt on this rosy image, causing even more confusion.

First, as The Verge discovered, Ubisoft has released a backward compatibility list that states that nine of its PS4 games will not run on the PS5. The full list is as follows: [However, hours later, the company retracted the list, telling The Verge that "Ubisoft titles playable on PS5 may contain inaccurate information."

While this withdrawal is good news, as it suggests that some of the games mentioned above may eventually work on the PS5, it also raises a number of big questions, as it seems fairly unlikely that all of the titles mentioned would have worked perfectly.

First, if Ubisoft needs to publish its own backward compatibility list, it is clear that the reassuring selection announced by Sony is far from perfect. And while they may not be interested in the "Assassin's Creed" spin-off, they may feel more strongly about Activision's and EA's back catalogs.

Second, two of the games on the list - Star Trek: Bridge Crew and Space Junkies - are for PSVR. This is alarming, as Sony had previously stated that the PS4 PSVR headset would work fine on the PS5 if one applied for a free camera adapter. Ubisoft's list suggests that things may not be so simple after all.

So what explains this disconnect between Sony and Ubisoft? Well, one possibility would be that the latter has higher standards for what constitutes a backward compatible game. After all, Sony's own explanatory article notes that "some PS4 games may exhibit errors or unexpected behavior when played on the PS5 console." Perhaps Ubisoft's original list included games with minor bugs that did not break the game, and the company was being cautious.

We won't know until Ubisoft releases its revised list, but if you were thinking of selling your PS4 right away, this may make you think twice. At the very least, streaming from an old console to a new one could guarantee compatibility.