Aion: how Microsoft envisioned a Windows without native apps, an alternative to Chrome OS

A three-minute video that surfaced on the BetaWiki Discord server revealed Aion, the codename for an internal exploration by Microsoft that imagined an operating system built from the ground up around Copilot. The images, according to sources close to the project, would show real but still nascent code, dating back to 2024.

The narrator of the video describes Aion as "an example of an agent-based web operating system that integrates Copilot at the very heart of the shell." The desktop interface resembles that of Windows, with a taskbar at the bottom and a Start menu replaced by a multimodal input pane through which the user searches for files, opens applications, and browses the web, all mediated by Copilot.

Among the features showcased is Spaces, an automatic grouping of apps and sites into a single icon on the taskbar, which can be accessed with a click. The same groups also appear in the Start menu, allowing multiple items to be reopened simultaneously with a single tap.

A Windows without native apps, reliant on the cloud

The version of Aion captured in the video runs on Win3, a streamlined Windows codebase that, according to sources, forgoes support for legacy Win32 apps in exchange for faster updates, greater autonomy, and enhanced security. The system does not run traditional Windows applications: it relies exclusively on web apps and sites, and for exceptions, it leans on Windows 365, the platform that allows streaming of a remote Cloud PC. The video also hints at a variant of Aion designed to run over Windows 11, which would presumably maintain compatibility with native apps.

Aion could have also been a simple experiment born out of an internal hackathon or, perhaps, something more structured. Sources describe the experimental project as conceived to test how far a desktop interface rethought from scratch around agent-based AI could go. There are no indications of Microsoft’s intention to turn it into a commercial product.

Some of the ideas tested with Aion, however, may have already influenced the agentic features that are arriving on Windows 11 in its current form. Microsoft recently announced Project Solara, an agentic experience that generates just-in-time interfaces based on user requests, running both on AOSP and Windows, not too distant from Aion’s logic. It is not ruled out that the latter simply evolved into Solara.

Would users appreciate an OS like Aion? It's uncertain, given the criticism directed at Copilot over the past two years, which may have prompted Microsoft to reconsider much of this setup. When asked about the project, the company preferred not to comment.