I'm thinking about making a "western" game. The problem is the core activity. I mean, there is a lot of possibilities: gunfight, mining gold, build railroads, become a sheriff, an outlaw, cowboy, farmer, etc. In short, if you want to put all the things players want you will never, ever finish the game (fantasy is so simple compared to this: red dragon, green dragon, black dragon, dragon egg, dragon sword, dragon slayer, dragon armour, dragonlance, etc

). I'm trying to find the core activity that will be appealing to many players but does not consume my 'time budget'.
I think they are two ways of doing this. First, concentrate on one aspect only (like you are a bounty hunter, and that's it). Second, make all professions but let them work the same way (so bartener and sheriff would use the same or at least very similar code), this could be done if the game is on a quite high abstraction level (like Princess Maker where you could select tons of professions and each changed some stats, but generally behave the same way).
Any ideas?