This was incredibly cool! I love how you've characterized the alien stranger. They're scary but in a fun, fickle, capricious sort of way... I don't get the sense that there's malice behind it, and that makes them so much more compelling.
I admit I did have to sneak a peek at the hint document to get the final ending. It pleases me to no end that stoking their curiosity is the way to convince them to spare you - it was the exact impression I'd gotten from their character!