Assassin's Creed: El Dorado-1R
After the American Civil War, everyone's eyes turned to the West, to the untapped resources on the other side of the Mississippi River. Among those who saw potential for this land were the members of the Templar Order who set out to conquer the West and bend it to their whim. They were installed as sheriffs and governors, mayors and marshals, some even taking on roles as gang leaders, in order to ensure the people knew that they needed law and order.
There were people there to oppose the Templars, however. The Assassins, as they had become known, though branded as outlaws by the Templar run governments, worked to bring them down and free the people from their grasp. However, moreover than freeing the people, there was one prize hunted by both sides. The Templars wanted it in order to fully realize their power. The Assassins wanted it to ensure that the Templars didn't get a hold of it.
That prize was the legendary city of El Dorado, said to be made entirely out of gold. That much gold would tip the balance of power in the West, and is the reason why both sides were willing to do whatever it takes to get it. The year is now 1889, and the Templars are winning the fight and rapidly closing in on the location of El Dorado. It's up to the Assassins to locate it first, and ensure that the Templars can never use what's inside.