An open world third-person game with RPG elements in the mold of GTA:San Andreas, with a Wild West theme, done relatively stereotypically, but not comically.

Based on your actions, you become an outlaw, a sheriff, a cowboy, a trader, or an explorer, or a mixture of those roles. Possibly a parallel development thread in an Indian tribe, too.

Wanted level is permanent and only reduced by doing time or by compensating with good deeds: becoming a deputy or sheriff; "cleaning up the town"; foiling a robbery, etc. Being lynched is a serious risk.

Your actions also will affect the growth of the settlements you visit, with buildings being built or torn down while you're out of the area. Misbehavin' too much in one town may cause it to become a ghost town. Establishing a trading route, either directly, or by providing protection on the way, causes towns to grow.

Mini games and missions would include lassooing; herding of cattle; gunfight duelling; protection; escorting; bounty hunting; stagecoach and bank robbing; prospecting; mining; hunting; train robbing (and protection); building a posse; and so on.

The landscape could be largely procedurally generated, as there would be a lot of prairie and desert. It should be as large as possible.

"Vehicles" go from a decrepit burro through to "Silver" as in The Lone Ranger, along with the railroad, stagecoaches, wagon trains, etc. Concern for your trusty steed's hunger, thirst, fitness and health -- along with your own -- is critical.

Weapons would include muskets, six-shooters, shotguns, bow-and-arrow, bare knuckle fighting, whip, lassoo (operated by rhythmic rotation of the analog stick), and sticks of dynamite.