It seems that Microsoft explored the idea of building Windows fully around AI in the past, based on a leaked video from a couple of years ago.

Windows Central highlighted a video (see below) that's a few minutes long and was leaked via the BetaWiki Discord server, with our sister site's Zac Bowden noting that sources have provided assurances that the clip is real. It shows an AI-focused version of Windows built around Copilot and apparently codenamed Aion.

The concept shown is a lightweight web-based OS, meaning it's built on web apps rather than native Windows apps. In other words, it won't run standard Windows (Win32) software, with the idea being to stream those apps to the desktop if they're required (meaning they're run from the cloud, or more specifically, Windows 365, Microsoft's cloud PC offering).

Whatever the case, Aion is still a thing, believe it or not: Microsoft revealed a new family of local AI models running with the same name at Build 2026. These are a "new generation of small language models that are smaller, faster, and more efficient than our previous Windows OS SLMs", as Microsoft explains here. Apparently, Aion lives on in some form, then, even if it's a very different idea to the notion of a full-on Copilot-based operating system.