I'm doing a game set in the American West during the whole cowboy time period (and gold rush), but with fantasy and mid-level magic. Anybody got any suggestions for .. anything?
Wizards of the coast has a mini mission called the red plague on their website. It is basically about a mine that has become infected with a terrible plague that is killing off the workers. That would be a perfect way to start. The party comes into a town. Buzzards circle overhead. People sway as they walk, their bodies so infused with infection that the town is on the verge of death. It would work fairly well as a starter for your campaign. Plus gives you some features to work into your city.
The old Akira Kurosawa film Yojimbo was remade into a Western called Fistfull of Dollars and might be useful to steal plot ideas from. They involve two rival crime societies tearing a town apart, and a powerful neutral force entering the town and tipping the balance. Rather than a lone gunman/ronin, the party could be the neutral force. The rival factions could be a thieves' guild and a wizards' guild. Basically the party would wander into the town and get propositioned to do some foul contract work by both sides. It's up to the party to play both sides against the other to take both organizations down and save the town.