The Sioux game may well become a Euro-game ... my first. If it goes in that direction, it would be a multi-player game where each player is in charge of a sub-tribe of the Sioux (Brule, Oglalla, etc.). The U.S. army has no player - their perfidity is played-out via the cards. At the begining of each turn (year), each player would draw a total of x cards from three distinct decks - a hunting deck, a trading deck, and a raiding deck (say, one from each, two from one and one from another, or all three from one). Players would use these cards to build up their tribe and, as you might expect, cards can be traded between players. You might get bonus draws from certain decks each year based on where you are on the board (for instance, if you're near Ft. Laramie, you might get a bonus draw from the Trading deck). Cards might be good or bad - and the really bad ones, for instance, might be a major campaign against you by the U.S. army. If the players don't help one another against the Americans, they're going to get creamed. But some tribes will be more militarily capable than others (if they draw from certain decks anyway, but if they do, they'll be weak in other areas), meaning you'll have to choose between when to help another tribe and when to let them hang in your own self-interest. Only one player wins - he who has the most tribesmen under his control at the end of the game. Could make for a very enjoyable dynamic.

But ... it wouldn't be a wargame.