You may have come across a game called 1666: Amsterdam in recent weeks, which is a new story-led action adventure title by the folks at Panache Digital Games - known for developing the popular Ancestors: The Humankind Odyssey.
Patrice Desilets was the founder of that studio, and he happens to be the creator of Assassin's Creed, serving as creative director on the original two games. He also assumed that role for 2003's Prince of Persia: The Sands of Time.
It stands to reason that Xbox would have been interested in publishing 1666: Amsterdam, then, and apparently it almost happened - a new report by GameFile reveals that Microsoft was in line to be the publisher at one point:
We also actually reported on a rumour about this a couple of years ago (looks like it was on the money!):