From site:
It is 1804. U.S. President Thomas Jefferson has asked Meriwether Lewis to lead an expedition across western North America, unknown territory for all but Indians. The goals: map the rivers, make friends with natives, open the West to trade, and look for a Northwest Passage (an easy water route from coast to coast).
Lewis and his colleague William Clark have chosen a special team for the journey, and youre invited! Up to the challenge? Then sign on.