UPDATE 16/11/15 12:15pm: There's some confusion about the status of Fallout 3 as an Xbox One pre-order bonus, and also the question of whether the code will expire or not. We've looked into this and can confirm the following: first of all, every copy of Fallout 4 available now includes the Fallout 3 code, and this situation is the case in every copy in every territory. This will be included with all copies of the game shipped in the first 90 days of its launch. Additionally, the code will not expire 90 days after launch - once you have the code, you can redeem it at any time. And finally, any initial stock that originally contained the Fallout 3 code will still have it once the 90 day period is over - it won't be withdrawn. Hopefully that clears everything up!

Original story: Microsoft released its new Xbox One dashboard this week, bringing with it the full public release of its remarkable Xbox 360 backward compatibility feature. An initial 104 titles are available, including Bethesda's Fallout 3, which is also given away free with the Xbox One version of its sequel. Once the current release mania has died down a little, we'll be taking a deeper look into the Xbox One backward compatibility feature, but we couldn't resist looking at Fallout 3 ahead of time - and first impressions are favourable.

To date, backward compatibility has been a bit of a mixed bag - a handful of games actually run better than they do on original hardware, while others can see significant performance penalties or strange visual artefacts. Based on a couple of hours of play, Fallout 3 looks to be one of the more successful titles to transplant across to Xbox One. Visual quality is effectively identical compared with the original game, and overall performance feels very, very similar for most of the duration.

Indeed, based on the evidence of our playthrough, there's actually a fairly compelling argument that Fallout 3 could be one of those rare titles that produces an improved experience on Xbox One. We noted a number of instances of the Xbox 360 version stuttering as we traversed the wasteland and roamed the town of Megaton, while in like-for-like situations, the Xbox One game seemed unaffected.

Also interesting is that in common with other backward compatibility titles, adaptive v-sync (producing screen-tear when frame-rate drops under 30fps) is not supported. Instead, Fallout 3 runs with v-sync running all of the time. On some games running under backward compatibility, this results in sustained drops to 20fps on games with a 30fps target, but Fallout 3 seems to avoid this and holds its frame-rate well, even in the more performance-sapping areas we tested. It's not a one-way street, however - occasionally, we saw a few minor performance drops on Xbox One unseen on its predecessor. Overall, across the bulk of gameplay, Fallout 3 seems to look and play exactly as it should on Xbox One. Indeed, we suspect that few would be able to tell the difference, even running side by side.

Outside of Fallout 3 itself, we rather like the features of Microsoft's virtual machine - in putting together the comparison, we were dreading having to replay Fallout 3's extended introduction sequence set in Vault 101. However, happily, after playing through on Xbox 360, we exported our saves to the cloud storage and they were automatically downloaded as soon as we booted the game on Xbox One. It's an impressive integration: the full gamut of Xbox 360 features is included in the backward compatibility engine, including Xbox Live functionality.

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In fact, the only aggravation we had concerned redeeming the code itself. The insert in the Fallout 4 packaging tells us that the code can't actually be redeemed on Xbox One - you can only claim it via original Xbox 360 hardware, or logging into Xbox.com. First, we tried the latter, producing a 'something has gone wrong' error message we finally identified as a region mismatch. Our chosen account is definitely UK-based, but we suspect our continual region switching on our Xbox One may have confused the website. Regardless, this left redeeming the code on Xbox 360 hardware as the only way forward.

We'll have more on this excellent new Xbox One feature soon, but since we produced our original piece on the beta, some details have come to light on how this impressive piece of tech actually works - in fact, we already published them, buried within our recent feature on the making of Gears of War Ultimate Edition.

We asked The Coalition's studio technical director, Mike Rayner, whether any optimisation or conversion was required in bundling prior Gears of War titles into the Ultimate Edition.

"It is essentially the exact same code," Rayner replied. "The Xbox team converts the 360 game and 360 flash PPC executables into native x64 executables, packages those up with the 360 game assets, 360 flash and emulator as a regular Xbox One game, and publishes it."

And this explains why we can't have immediate backward compatibility access to every Xbox 360 game in our library: the Xbox team itself seems to be recompiling the original PowerPC code to run on the x64 AMD Jaguar cores integrated inside Xbox One. This revised code is then bundled with the original game assets, along with x64-based versions of the Xbox 360 OS itself. [UPDATE 16/11/15 8:51am: Reader L_A_G writes with another compelling theory: that the source code isn't being recompiled, but instead a binary translator is used instead.] In effect it seems that the Xbox team is able to quickly produce streamlined ports of original Xbox 360 projects. It's a remarkable achievement, and perhaps also explains why so many simpler titles are in the initial batch of backward compatible titles.

Plans are afoot to bring more challenging games to the virtual machine though - based on the list seen here - and the software-based nature of the system, not to mention the x64 recompilation technique, all suggest that performance and incompatibility issues on certain titles could be improved over time, though in the short term we suspect that expanding the library will be the Xbox team's primary objective.