Now, I haven't done this yet, but I want to take Fiasco and create less hostile games. The format is good for this. In your case, you could give people the characters from your story, give them a location and known relationships. Give them a goal (escape the cannibals, reach the town within a week before running out of food, etc.). Then let them play with the scenario. Your players would then be bringing the characters to life. Perhaps not directly mimicking the story that you had intended, because it's more freeform and player driven, but you can maybe get an idea for how your characters actually are as people.
Fiasco = Improv RPG. That's my way of describing it, at least. The rules as written are around tragic, horrible things happening to flawed people (literally, at the end of the game you roll your dice to determine your fate: worse than death, dead, in prison or similar, etc.; then you create a story to explain that fate, maybe you died in the game, maybe you died after when someone else came after you for revenge).
But I have a strong feeling that this could be converted into something less tragedy focused, if you can get player buy-in.
http://www.lamemage.com/microscope/
(we built a crazy setting somewhat reminiscent of "The Expanse" (independently) which we used for a bit of swashbuckling sci-fi - sort of "Firefly" meets "The Martian" meets "Ex Machina").