Major Nelson Talks Challenges Of Xbox One Backwards Compatibility

Major Nelson and Bill Stillwell of the Backwards Compatibility Team delve into the technical side of Backwards Compatibility on the Xbox One in Major Nelsons latest podcast.

The first half hour is dedicated towards backward compatibility (BC) and it's a very good listen and a rare peek into the otherwise secretive program. You can find the whole podcast below.

They said there are over 1800 Xbox 360 games that have been released so far. Roughly over 280 of them are now backwards compatible. 300 backwards compatible games is their goal for the end of 2016.

For those that want the podcast in quick bites feel free to read the below.
-The first half hour is dedicated towards backward compatibility (BC) and it's a very good listen and a rare peek into the otherwise secretive program. For those of you who can't listen to the podcast, I've written notes covering the interview with Bill Stillwell:

-Originally prototyped by a group of passionate engineers.

-One of the first games demoed internally was Castle Crashers, which also served as a good model for multiplayer and local co-op.

-Project Fission was the name for getting the base 360 instruction set to work on the ONE. The architecture change from the 360 to Xbox One meant translating PowerPC code to x64.

-They still have to go through games on an individual basis to check if the emulator can handle the various physics engines, loads, etc. For example, at one point they got Forza Horizon running flawlessly through the emulator but comically, there wasn’t collision detection and you could drive through everything. Working on correctness or precision through the emulator takes away from performance, so the challenge is to strike a balance between the two.

-Pre-E3 2015: The BC team was terrified of a leak. They were amused whenever people on reddit or neoGAF would speculate on backward compatibility but immediately shot down by others citing Microsoft's previous statement that BC was impossible.

-E3 2015: They decided on showing off backward compatibility with Mass Effect 1 because of its reputation as a beloved title. The only downside to this were people forgetting how poorly it ran on the 360 and now blaming the low framerate on the emulator. One joke was that should've secretly swapped consoles to play ME1 on the 360 and revealed the switch whenever anyone complained about the performance.

-For the BC team, it was rewarding to see the audience’s reaction to the reveal during the E3 conference. Bill Stillwell said there was a massive intake of breath among the crowd followed by an eruption of celebration.

-Stats: Launched Nov 2015 with 100 games. Currently over 280 games backward compatible. The goal is 300 by the end of the year, but no promises. 210 million hours of playtime logged through BC on the Xbox One.

-A large part of their workload is “republishing” every game (including DLC and all region variants at the same time) that goes backward compatible. This technically makes the BC team the largest publishing studio at Microsoft.

-The list of games voted for backward compatibility on UserVoice is their primarily source for ranking and prioritizing which games to put through testing. But the ease at which to make them perform perfectly in the emulator determines how fast each game is released. No game is held back and they do take into account which titles people really want.

-When a 360 game is selected for BC, testers have to play through the entire game to collect data. As the game is further worked on, testers have to complete multiple full playthroughs to test modifications to the emulator, evaluate performance, search for bugs, etc.

-They also have to communicate with publishers over IP rights and music licensing (Game DVR). Some publishers during the 360 era are now defunct, posing an additional challenge in tracking down who owns what. For example, THQ’s properties were scattered to the wind and bought up by other publishers.

-Their legal team has to navigate through this Wild West of old middleware contracts behind each game, performing the due diligence necessary to make sure everything is legal in accordance to IP laws. Unfortunately, this means sometimes running into the most illogical of legal issues as a result of weird contracts. That said, they have gotten great third part support and all publishers want to participate.

-Another obstacle is tracking down and analyzing all the different versions and SKUs of BC games like GOTY, Platinum Hits, promotional, etc.

-Sneak King (and the other Burger King games) are especially difficult to make BC because they were not printed on Mirosoft’s traditional encrypted discs. Xbox Live uses that encryption as the identifier for each game, so there is currently no way for the Xbox One to recognize those discs. They’re looking into a solution.

-Each time they update or improve the emulator, they retest some older BC games to see if they can fix known issues. For example, they updated the BC version of Halo Reach after they saw performance gains with an updated emulator.

-Roughly 1800 total Xbox 360 games.

Related Forum: Xbox Forum


"Major Nelson Talks Challenges Of Xbox One Backwards Compatibility" :: Login/Create an Account :: 19 comments

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i reckon mw2 isnt backwards compatible because it will be getting remastered


pretty insightful into the why some games are not bc yet or ever


I really hope that some great games come out for BC. I miss old 360 games


GTA IV backwards compatible please


MW2 for the win. though I hope they actually do a remastered MW2 and sell it alone


Wulca MW2 would be great to see come out on the Xbox platform. There will be more players I recon playing MW2 and MW3 I think?

I would honestly rather a remaster of MW2, after MWR, I have full faith in a unreal good remaster of MW2. However I would like MW2 and CoD4 to still be BC regardless.


MW2 would be great to see come out on the Xbox platform. There will be more players I recon playing MW2 and MW3 I think?


I just want good games, not no name games.


DoctorStrange I hope mw2 comes out as BC.

To be honest I'd rather see MW2 Remastered than it come out on BC so everybody would have to work for their unlocks other than everybody being 10th prestige with all unlocks.


I hope mw2 comes out as BC.

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