This is probably one of the most overdone blog topics here but I might as well just express my opinion on the different settings where Assassin's Creed could be placed. These are more on a personal than realistic aspect.
- Feudal Japan - This remains to be one of the most popular suggestions by the fans. But would it not be kind of overdone? Would the ninjas be dressed in black with super-ultra reflexes and random backflips when they're engaged in combat? If they ever did that I would guarantee you that I would not get that game. One reason I love the franchise is because of its historical value. Ninjas never actually did wear all-black.
- Victorian London - Again, this is a popular time-period by the fans. There could be a chance of lots of historical cameos as well. Could Queen Victoria be a Templar? Could there be a chance of a stealth mission involving Jack the Ripper? Could Thomas Edison be the Leonardo da Vinci of London? Maybe the protagonist be a poor orphan child who sleeps rough? Or maybe it could be a child born in to nobility but sees their evil ways and joins the Assassin Order? The game could have secret societies, people of all different economic classes, occassional use of firearms, tall buildings and underground systems. It seems to tick all the Assassin's Creed boxes. Maybe the Apple of Eden could be the Crown Jewels?
- French Revolution - People have been wanting this setting more after Assassin's Creed III. Maybe this setting could be for the next spin-off and we'll see a return of Connor? Ubisoft already laid the foundations by doing the American Revolution so not doing the French Revolution would be like thunder not following lightning. It holds similarities with the Victorian London setting - monarchy, different social classes and fabolous architecture. Louis XVI and Marie Antoinette reigned over France. These could be Connor's enemies. And then ten years later, Napoleon led himself and his army against Britain. Marquis de Sade was still around at that time so maybe he could step in to the 'genius' slot. But could it provide for a good gameplay experience? Why would someone want to use all their assassin skills to just see in the end a fat king executed by another hand?
- The Mayan - This is a location I'd enjoy, mainly because I love ancient history. If they set it during the Spanish Conquistador era there would be a lot of room for development. In fact, Assassin's Creed II was almost going to be set during the Mayan times. It would have tied in perfectly with the whole 2012 Apocalypse thing. There could be artifacts like Crystal Skulls, the storyline could be similar to Assassin's Creed III, you seeking revenge against the Conquistadors after they destroyed your home. But would the game provide? Back then there wasn't huge amounts of buildings so if it's on the Mexican Maya civilization it could be very barren, but maybe if it's on the Guatamala side of the Mayans there would be jungles filled with all kinds of exotic creatures. In both locations there was the landmark Mayan pyramids. Huge structures with a long trail of stone steps leading up to them. At the top they usually conducted sacrifices. The Mayans were slightly visited on in Assassin's Creed III so it could be a potential candidate.
- World War II - Alas, this would be my least favourite place to set Assassin's Creed. Mainly because the use of firearms was so widespreas back then. "You have a hidden blade? Well tough luck I have a flamethrower!". "You want to escape the city? Not if I have an atomic bomb!". Yes Hitler could be a Templar. Yes Hitler did collected old artifacts which could contain the Apple of Eden. Yes you could set it in the Alps pursuing him. But guns, guns, guns just echo throughout this. "Then why don't you just give the protagonist a gun?". Well then this would just destory the franchise's roots. It would just be like a version of Call of Duty in a third-person style with parkour.