Alright, so here's the deal: You come up with an Assassin's Creed spinoff, it has to revolve around actual history and use real people as Templars/ Assassins. The protagonist doesn't have to be a real person, and there doesn't need to be any past/2012 connection in terms of ancestry. Bonus points for incorporating pieces of Eden. I heard the GB community has some creative people, let's see what variety they can bring to the table!

There are a couple potentials I'd like to see, but the one I'm thinking of just now would have Robin Hood as the protagonist. 
 
Robin Hood would battle Templar forces trying to usurp the throne while Richard was out on the crusades.  You'd have a map system similar to the first game... an over world (Say Sherwood forrest and surrounding countryside) with entrances to each city.  Fast Travel would open up after the first visit.

 @Reizarvg:

 @applet0n: Well Robin Hood runs the same risk as being too similar to the first too considering it is happening at basically the same time, just back in Europe.  The other complication is that I'm not sure the Assassins were a globalized  (or at least known-world-ized) organization, I'm not too up to date on the lore beyond what I've heard in the games. 

As far as the ranged focus goes, the game really could use a deeper ranged weapon interface but we shouldn't forget that Robin Hood (as portrayed in the legends) isn't just a master archer, but a master of many weapons killing proficiently with a sword and improvised weapons... and besting 'Little John' with a staff he presumably had little experience with, so the focus wouldn't need to be changed so much as just improving the ranged weapon element in the game... give more focus on accurate shooting, make us work for our op bow/xbow kills. 

The 100 years war setting would be interesting given the mix of politics and religion at the time in Europe, plenty of people they could name drop in the game for that pseudo legitimate feeling they have nailed thus far.

All I want is a female protagonist.

A music game spinoff set in the 1970s when Templar disco artists such as the Beegees use Pieces of Eden to create popular electronic dance music, with Templar propaganda back masked into it. You play as the assassin Frank Zappa on a quest to restore rock as the popular form of music. 

" A music game spinoff set in the 1970s when Templar disco artists such as the Beegees use Pieces of Eden to create popular electronic dance music, with Templar propaganda back masked into it. You play as the assassin Frank Zappa on a quest to restore rock as the popular form of music.  "

" @XII_Sniper said:

" A music game spinoff set in the 1970s when Templar disco artists such as the Beegees use Pieces of Eden to create popular electronic dance music, with Templar propaganda back masked into it. You play as the assassin Frank Zappa on a quest to restore rock as the popular form of music.  "

Amazing. "

Old West. You play as Billy the Kid, hunting down various scum bags.

My spinoff would be called assasin's creed 3,  it would basically be uncharted third person shooting combat with building climbing and cool assasination moves.

" There are a couple potentials I'd like to see, but the one I'm thinking of just now would have Robin Hood as the protagonist.  Robin Hood would battle Templar forces trying to usurp the throne while Richard was out on the crusades.  You'd have a map system similar to the first game... an over world (Say Sherwood forrest and surrounding countryside) with entrances to each city.  Fast Travel would open up after the first visit. "

I was going to say that it should be about Desmond globe trotting with shifty characters whilst searching for ancient treasure, but that's pretty much the same as Uncharted.  
 
So Uncharted is my AC spinoff.  
 
For all I know that may be how Brotherhood ends (haven't played it yet). Actually, that's how I hope it ends. With the series turning into Uncharted. (not really). 

Feudal Japan, ninjas.  Buildings built to stop people from climbing said buildings.
 
It's not like we're ever going to get a good Tenchu again anyways.

Assassin Beer Tapper coming in 2020.

"Assassin Beer Tapper coming in 2020. "

It would take place on the moon, and you would play as Neil Armstrong. We don't know what really happened up there.

Going back to before Assassin's Creed 1, where you play as Jesus Christ. The first assassin. He's not converting people to Christians, he's converting them to assassin's where he will take on the Romans(or whoever killed him) who are actually templars looking for a piece of eden. 
 
Or God makes the piece of eden and has Jesus protect it to which he fails after his crucifixion and the templars get one but all the other pieces are spread over the world.

i was totally pumped when the rumors were going around about AC2 being set in the French Revolution. Would like to see that. Also maybe something more modern like The American war of independence or the Civil War. It would all depend if you could keep the game play fun/not impossible when guns are introduced.  

Before Templars and all whatnot, Caesar had a piece of Eden, and it turned him into one of the greatest statesmen of all time. 
 
But, through his secret networks, an ambitious upstart named Brutus, formerly Caesar's confidante, learns about Caesar's methods. Brutus equal parts hates the idea, and wants to take it for himself to create a better empire. Forced to go undercover for a spell, Brutus interrogates, scraps, and assassinates people associated with Caesar in order to learn the truth. Part way through the game, Brutus begins to build up a group of conspirators to help him. This includes people like Cassius, Casca, Trebonius, and Metallus Cimber. As people close to him start to disappear, and civil unrest begins to grow, Caesar becomes more paranoid, employing more guards and executing more citizens accused of treason. The final part of the game is an assassination mission that involves killing Caesar while he is under very heavy guard. The mission plays out like an open-ended, multi-part heist. Getting close enough to Caesar can be done numerous ways, involving disguises, secret passages, or straight-up fighting most of his guard. Upon killing Caesar, Marcus Brutus takes the Piece of Eden off Caesar's person and escapes. Just like at the end of the Shakespeare play, he commits suicide on the battlefield some time after. 
 
Later, in a sequel that takes place 200 years after this game, it becomes apparent that this particular Piece of Eden has somehow come to be held by a tribe of Visigoths. This game is about the final battle of the Gothic War with Rome, which is actually staged in order for the Goths to take the remaining Pieces of Eden from Roman control. Early on, it is revealed by a Roman turncoat that after Caesar's demise, his successor as Pontifex Maximus, Marcus Aemilius Lepidus, begins a search for more Pieces of Eden. This tradition continues until shortly before this game takes place, when Emperor Diocletian abolishes the (up to this point) state sanctioned group who are looking for the artifacts, for fear that someone else finding a Piece of Eden could be a great risk to Rome.
Being a Goth yourself during the Battle of Adrianople, you leave your tribe and become a solider in the fight against Rome. Taking to the battlefield, you fight Emporer Valens's foot soliders, his generals, and finally, Valens himself, who has three artifacts, and is thus quite powerful. Seeing first hand the grief that these artifacts cause, the protagonist makes it his mission to keep the artifacts from falling into the hands of these kinds of people, so that they could not the power they hold. He creates a group who share his goal, and they continue to find, and hide a bunch of artifacts until they are all killed by Templars several hundred years later. 
 
I didn't even play AC2, so there is a good chance that none of this make sense, but at least it killed some time while I waited for KOTOR to download.

My spinoff would take place in London around the 1890's or early 1900's, I really liked exploring Rome and would love to run around a fake London.  Since it doesn't have to exactly tie in with the main story or be real at all the protagonist would be Sherlock Holmes trying to figure out the mystery of the Pieces of Eden.  Now you man not be assassinating people but you could still beat the crap out of them and could use Watson as an assist character.  Your eagle vision could help you find clues and use your acrobatics to sneak into places to look for clues too.   
 
Hell you could even be playing as Jack the Ripper running around London assassinating people and you find out that he wasn't a bad guy at all just playing his part as an assassin.  Mainly I just want to synchronize over London on BIg Ben.  

Cold War Era Assassin.... Russian Assassin group versus an American Templar group. 
 
My dream.

 @ooochoa: Sherlock Holmes would make a good assassin... he'd never leave any evidence to be found.  He also has built in villains, the issue I see though is the Sherlock Holmes IP might not be available / affordable...  I'm not sure how that works really, or if it is old enough to be open domain.

@zereta:  There's a pretty big problem with that wish.  The Assassins don't take over or control governments, they operate as an independent faction.  This is true for the Templar as well but for the exact opposite reason.  The Templar don't pick a side, they control ALL the sides.  In World War 2 Hitler, Stalin, Churchill, Mussolini (suspected), and President Roosevelt were all Templar.

" My spinoff would take place in London around the 1890's or early 1900's, I really liked exploring Rome and would love to run around a fake London.  Since it doesn't have to exactly tie in with the main story or be real at all the protagonist would be Sherlock Holmes trying to figure out the mystery of the Pieces of Eden.  Now you man not be assassinating people but you could still beat the crap out of them and could use Watson as an assist character.  Your eagle vision could help you find clues and use your acrobatics to sneak into places to look for clues too.    Hell you could even be playing as Jack the Ripper running around London assassinating people and you find out that he wasn't a bad guy at all just playing his part as an assassin.  Mainly I just want to synchronize over London on BIg Ben.   "

" Cold War Era Assassin.... Russian Assassin group versus an American Templar group.  My dream. "

Abraham Lincoln battling the Templar known as Robert E. Lee. The rest is history.

A prequel with Desmonds dad or granddad.

Read my status :P  But to expand on that, the story could be the Templars' reach has extended to Japan in the form of Samurai and because of this, the farmers and peasants (which is what most real ninja were) were approached by the assassins from Eastern Europe and trained in the art of assassination, and therefore ninjas were born.  Then ninjas killed Templar Samurai.  We haven't had a great Tenchu game since PS2 era.  I however enjoyed Tenchu Z a lot since I'm such a ninja fanboy...
 
Some may say ninjas are played out, but I really think these dudes could capture the feel of a real-life ninja that dressed as a civilian and not the stereotypical black bodysuit.  Fuedal Japan really just makes sense.  And if they wanted to make another trilogy, modern Japan, as Jeff mentioned, would make for a good modern AC setting.

What would be cool modern landmarks to see Desmond climb on? The CN Tower?

They should take the game to ancient egypt.  The weapons would suck but theres some great room for assassins tomb missions and a nice dynamic international history.  That and Ancient China or Feudal Japan.