Gamespot dug up the trademark, which the site speculates could be in reference to the Great Fire of London.
Of course, other events occurred in 1666, including the Four Days' Battle, one of the longest naval engagements in history. Plus, we could totally go for a fresh take on The Ancient Art of War at Sea.
We were also curious if it's even kosher to trademark a number:
"Why yes, you can. The mark just has to be attached to a product, so even a number can be a mark. It happens all the time with cars (F150, 328i, M3, e55, A4, IS350, etc.) and often with other 'model number' kinds of instances," former Law of the Game columnist and actual lawyer Mark Methenitis explained.
"The important thing to remember is the mark only applies to the list of goods (in the case of 1666, the list is more or less "video games"), so while I couldn't make another game named 1666, I might be able to make a movie and I would certainly be able to make a set of kitchen utensils or a perfume called 1666. Those are a completely different kind of good unlikely to be confused with the game -- or at least I would assume; if the game is about a chef with a perfume fetish, maybe not."
This is the second time a trademark filling by the financially troubled publisher has popped up in recent memory, with "Evolve" showing up a couple weeks ago.