In 2024 or earlier, Microsoft was working on a Copilot-centric operating system codenamed "Aion," a web-based system running a modified version of Microsoft Edge. This meant it wasn't a standard Windows operating system, but rather Microsoft Edge, built on Chromium.

A leaked video circulating on the BetaWiki forum and later published online clearly showed this Copilot OS abandoning the traditional Start menu in favor of an AI-centric model called "Sydney," which was entirely focused on artificial intelligence. Sydney was the codename for Bing Chat (the original Copilot service).

When you first launch Windows 11, the Start menu, desktop, and taskbar icons appear. However, in the Copilot OS codenamed "Project Aion," there are no desktop icons, but there is a Windows 11-like background. The taskbar is very minimalist, with a single colorful Copilot-style icon in the center that serves as the Start button. If you recall, Satya Nadella previously stated that Copilot would eventually become the Start button, and the leaked "Project Aion" appears to be built with this in mind. Upon closer inspection, you'll notice that Copilot OS, which has likely been canceled or postponed following recent leadership changes at Microsoft, bears some resemblance to both Windows 11 and ChromeOS.

Depending on what you request from the Omnibox, the system decides whether to securely route your query to the enterprise version of Copilot for business data or to the consumer version for general web queries.