"Odyssey (also known as NT6) was the codename for a version of Microsoft Windows that was intended to succeed Windows 2000. It was cancelled sometime in 2000 and was merged with Neptune to create Windows XP.[2]"
Development
"Development of Odyssey began alongside the consumer-based Neptune project in 1999 and was based on the Windows 2000 codebase.[2] Features planned for Odyssey were the new Activity Centers as well as a new user interface.[2][1] The version number of Odyssey is unknown, with some unverified sources claiming it as NT 6.0 or NT 5.5.[3]
Due to high hardware requirements and because Odyssey and Neptune were built on the same codebase, Microsoft combined them to form a new product codenamed Whistler, for efficiency.[2] No builds or versions of Odyssey were ever leaked or released by Microsoft as the product never left the planning stage.[3]"
"Confidential documents from the Comes vs. Microsoft case do state that Odyssey was indeed under development."
https://en.wikipedia.org/wiki/Windows_Odyssey