Windows Odyssey

Windows Odyssey was planned as new business version of Windows NT, but never came off the drawing board, as it was soon canceled alongside Neptune. The kernel version is unknown, though some say NT 6.0 and others say NT 5.5.
The team working on Odyssey was merged with Neptune's team which lead to the creation of Codename Whistler (ultimately released as Windows XP) which has two main editions, namely Professional and Home Edition, but there are also several different other SKUs.
One Alpha build of Neptune was released to the public (# 5.50.5111), but Odyssey is only mentioned in the Microsoft Vs Comes documents, but even they are unclear as to what exactly Odyssey is and it appears to change between the handful of times it is mentioned. However, the most common occurence suggests it was actually a major update to be delivered after NepTune and Triton (which was scheduled to be a minor update to Neptune).