Dang, quantum vampire is a cool idea. Evocative descriptions and exciting concepts.
Good integration of mechanics. I liked how different skills conferred bonuses or provided clues.
I really like how you incorporated scientific concepts into gameplay. Decoherence is great. Being forced to essentially reroll your character as you play is really clever.
I also liked how you used quantum superpositionality for multiple gameplay mechanics! But for defeating the immortal, I though that the clue may be a little too vague. Maybe instead of "Bullet through the head," it could be "Bullet through its head," since when I first read it, I immediately though it meant bullet through your own head.
You even specced out the ship so players can use it. This is just so good and well thought out.