Check out a short story made by @FearTheFuzzyBear
with only three words I've suggested! Betrayal, cursed, freedom.
What great writing! (Yeah, I mainly posted the link here so I can always refer back to it. Not my fault though! D:) You got to check out her other stories! Not to mention the Medusa and particularly Cursed! I mean, even I can't write like that! Such cliffhangers. ;-;
You could also offer three words they can make a story with. Only one per week though I heard. But I guarantee it'll be of good quality. ;)