Windows 9 — What (Probably) Happened

Based on many months of research, time, effort, and sometimes; pure luck.

Adam (Futur3Sn0w)
6 min readMar 15, 2022
Estimated Windows 9 Timeline


Before You Read:

Mentions of ‘we’, ‘our’, and similar reference those involved in research effort conducted by me on behalf of my own Studio30. The names of those who contributed have been intentionally omitted, but may be added back in as references upon request.

Similar to above, mentions of ‘me’, ‘my’, ‘I’, and similar are talking about the author of this article, Futur3Sn0w (myself).



I know it seems strange. “Windows 9? We didn’t have Windows 9…”
Put simply; You’re technically correct. Technically.
See, it’s not as simple as “it didn’t exist” because; we truly don’t know that with 100% certainty.

In fact; as of Sunday (March 6th) of this week, the certainty of Windows 9’s existence increased exponentially; which takes us quite nicely (akin to LinusTechTips) into our first topic:

The “Big Discovery”

Aside from the recent discovery of the (presumably) Windows 9 naming (see Neowin article¹), the early Windows 10 builds (anything with NT 6.4; see part 3 below) are actually development builds of, what enthusiasts would know as Windows 9. The internal codename “Dark Blue” was used (following Windows 8.1’s “Blue” codename.).
They are as close as the public ever got to a Windows 9.
This implies that Microsoft intended to ship it separately to some degree, but decided to roll it into the next major update; being Windows 10.

The (very) early development resembles something similar to what happened with Windows Longhorn. As more and more features got added and more of the ecosystem evolved, Microsoft decided — rather than trying to keep it as Windows 9 — to make an even bigger leap to Windows 10.**

All that being said, a “compromise” release² still technically could have been possible, and in my own opinion, should have happened. This would’ve been a great sendoff, if you will, to Windows 8.1.

It’s unclear what the final reason behind them inevitably deciding against this was, but the evidence of them going forward with it was actually tested in Windows RT 8.1.

And so brings us to —

Part 1 — Lets talk a bit about Windows RT.

In 2014, Update 3 for Windows RT 8.1 was released, bringing the Windows 10 Technical Preview Start Menu to Windows 8.1.

This (vaguely) suggests that Microsoft had at some point in time the intent of bringing that specific Start Menu as an update — sometime between 8.1U2⁵ and Windows 10 build 9841 (First official Technical Preview build).

This is about a 2 month period (August 2014 — October 2014), and may explain why instead of getting 8.1U3⁴ alongside the first Win10 TP build, it instead released in November. It (likely) also explains why 8.1U3⁴ was a quiet release, since it didn’t include many huge features as it could’ve.
We suspect that they thought the new Start Menu was ‘too big’ a feature to bring to a feature update.*

Part 2 — The Non-XAML Start Menu and Windows Server

If you haven’t seen it in action, the Start Menu of that time (aka the Non-XAML Start Menu) is very reminiscent of the Windows 8.1 Start Screen, and in the opinion of some enthusiasts (including myself), was better than what eventually shipped with Windows 10 RTM.
It was quite a different experience, and it seems strange that the full implementation of the Non-XAML menu didn’t ship on anything other than RT.

That said, it did stick around for an insanely long time. It was in Windows 10 TP for a handful of builds after the XAML menu was enabled, and with Windows Server 2016, the code (and subsequent registry hack to re-enable it) persisted until at least Server build 10014⁷.
After this point (in 10244, specifically), the codebase of Server ’16 transitioned from the original Windows 10 codebase, to the Anniversary Update codebase⁶.
There’s lots of hearsay about people re-creating or porting the menu, but very little concrete evidence has been documented. I did think this was relevant information though.

Part 3 — NT Timeline

This may not make sense to those who aren’t aware; every single build between (at least) 9810 and 9883*** utilize an NT version of 6.4.

We believe that these are Windows 9 (codename “Dark Blue”; see first paragraph) development builds. This is another huge factor in favor of Windows 9’s existence as it followed a similar pattern to the transition from Windows 8 to 8.1.

Now, as for builds pre-9810, we believe anything between the RTM of 8.1U3⁴ and build 9810 with the NT version of 6.3 are actually that “compromise” release² discussed earlier.

Conclusion: It’s all hypothetical.

Despite the recent discovery of the ‘Win9’ name in the newest Dev builds, pretty much everything is completely hypothetical, and honestly, at this point, rather moot. The biggest reason it became interesting to us is because of that discovery; that’s about it.
If you currently use, or have ever used, the partner_eeap builds of Windows 10, you’re getting the most polished Windows 9 experience that exists³.

It’s always interesting to learn about the history of Windows, and being that NT6.3 builds will forever be my personal favorite Windows builds (of all time), we have thoroughly enjoyed doing research on what Windows 9 could’ve been.


Quick Q&A:

Q: [Would it have been] called Windows 9?

A: At some point, yes. There was a period of time when it was called Windows 9, with the codename Dark Blue (see the first paragraph). Although, after deciding to roll it into (what became) Windows 10, the plans obviously shifted and changed to justify a new release of the software.

Q: How do you know all this?

A: I’m going to be honest, we have drawn a few conclusions based on information found in those early 10 builds, articles from the time, and various other sources.
That said, we did not invent or come up with any theories that weren’t explicitly stated as such. Anything we concluded was all based on research we did.

Q: Why are you so focused on the Start Menu?

A: The Non-XAML Start Menu is the best point of reference for the different variables in this article. (Switch from Technical Preview to Insider Program, Non-XAML to XAML menu, Update 2–3–4, etc.)
It makes it a bit easier to reference different things based on context.
Obviously, the Start Menu wasn’t the only user-facing feature of Windows 10, but it was one that stuck around the longest, and had such an important history relevant to the rest of the article (its appearance in RT, its persistence through server builds, etc.)


If anything in this article is unclear, or if you’re confused by anything, please reach out on Twitter or via Email. I’m happy to respond to both to clear up anything.

Additionally, if you have any information to add, or you have a clarification to something in the article, please also use the above contacts.
Any information contributed after-the-fact will be added with a flag to the person who contributed it.


Links and references:

²: Windows 8.2, or Windows 8.1 Update 4
³: To the public, as of March 2022, without a timebomb.
⁴: Windows 8.1 Update 3 (aka. the November Rollup)
⁵: Windows 8.1 Update 2 (aka. the August Rollup)

*: This doesn’t, however, explain why it did make it into Windows RT 8.1 Update 3. Maybe they already knew the OS was DOA?
**: Presumably, in an effort to prevent what happened with Longhorn.
***: These builds are subject to change as more research is done, and more builds are discovered to exist outside of Microsoft.



Adam (Futur3Sn0w)

I’m Adam, better known online as Futur3Sn0w. I’m a graphic designer and (sometimes) music producer/DJ. I also moonlight as a writer!