Found a new site, Writing Prompts That Don’t Suck.
Here’s one:

Start your story with this sentence:
Every morning I wake up in the armpit of this alien world.

Every morning I wake up in the armpit of this alien world. The local’s call it Gallup, and I’m not sure if that’s a reference to the four-legged beasts that they ride or the dysentery caused by the less than sterile facilities. At least they have paper in the loo, so it’s a half-a-step above that primitive hell hole I was sent to on my last mission.
My mission this time is to find some guy named Carson and prevent him from killing some other guy, a shaman or something of the indigenous tribe, and then prevent him from ruining said tribe. It’s always a drag to be on the invaded’s side instead of the invader’s side, you know what I mean. But the relative future of the Empire is relying on this Niyol [wind] to calm the native spirits who happen to be in charge of the trade lanes.

Thoughts: This is a man from the future where space and cowboys happen. The native american races have territories and the Empire (like the federation in Firefly) has to deal with them in order to pass their territories. It impedes trade. To make the trade deal happen, the native americans in space demand that the Long Walk be prevented.

The West:

Sent to punish Navajo raiding parties in northwest New Mexico, Colonel Kit Carson leads a campaign of destruction through their villages, burning crops and killing livestock. When the Navajo surrender, he marches 8,000 of the tribe on a grueling “Long Walk” across New Mexico to a parched reservation near Fort Sumner on the Pecos River, where they are held as prisoners of war until 1868.

Kansas Monolith

Kansas Monolith