Kurt and Katie, this looks great. I had four thoughts about the rules for emotions and rolling dice, though.
Persistent emotions: What are your thoughts about making each PC's emotional journey more consistent? I'm thinking that rather than having them choose their emotion at the start of the scene, it might be good to retain whatever emotion they finished the last scene with.
Centering the size of the emotion die around your emotional state: Am I reading it right that the Green emotion is always a d8? Or is it that your current emotion is a d8, the ones on either side are d6s, and everything else uses d4s? I think that second option might create some more effective variations in the dice that players roll for conflicts
Failure: What if, on a failure, you could choose to succeed but flip to one of the two extremes (Hot or Cold) on the Emotion Spectrum (maybe on a Snake Eyes result you fail and have to flip?)
Exploding dice: I see these as kind of like a triumphant montage sequence or a series of close-ups of a PC achieving something incredible. I'd want each time a die explodes to be more more significant. Have you considered something like "Each time a die explodes, choose either your PC or another PC who is with you. They can either shift their current emotion one space left or right on the spectrum, or clear a condition, or clear a stress mark."
(Cross-posted to the Indie Games Reading Club slack.)