Update 2/24: Microsoft has offered tons of new details about the Xbox Series X, including additional confirmation that its backwards compatibility will extend to all four generations of Xbox.

Original story follows...

If you've spent the past few years collecting and playing a vast library of titles on Xbox One, then don't worry--that collection is all coming with you if you choose to upgrade to Xbox Series X (the official name of Project Scarlett). Xbox Series X will support backwards compatibility for Xbox One games right when the next-gen console launches during Holiday 2020.

"We wanted to make sure we had that, day one, we could deliver on the compatibility promise, and so I've been playing quite a few [Xbox 360] games on my [Xbox Series X] and Xbox One games on the [Xbox Series X] and that's just to ensure that we can be there day one," Xbox boss Phil Spencer told GameSpot.

"We have thousands of games that run on Xbox One today," Xbox partner director of program management Jason Ronald told GameSpot. "We want those games to be able to come forward with you but we also want your services to come with you. We want your gaming legacy to come with you, whether that's your Gamerscore, whether that's your friends list, all your Achievements, your game saves, all of that should come forward so there are no barriers for you as you think about moving forward."

The process of ensuring three previous console generations of games all play on Xbox Series X has been a lot of work. "There is work in ensuring [backwards] compatibility across those generations," Spencer said. "So, as you might remember, we slowed down and paused our backwards compatibility program for [Xbox 360] on Xbox One."

"[It takes a lot of work] even for Xbox One games, because one of the biggest challenges is console games are usually hyper-optimized to the unique hardware capabilities of the device, and this is a new generation of hardware," Ronald added. "It is a new chip architecture. At the same time, we did design the silicon with [backwards] compatibility in mind, so we did make certain decisions to try to lessen that work, but I don't want to trivialize how much work the team's actually doing because there is a tremendous amount of work."

With the Xbox Series X officially revealed, our comparison between it and Sony's PlayStation 5 has become a little more concrete. If you need a little refresher on the console, we've compiled everything we know about Xbox Series X--from its announcement as Project Scarlett to its The Game Awards reveal.