Nice concept. Took me a few iterations to figure it out. Wasn't expecting a boss-fight at the end, but managed the first time. Then I redid it once more, to make my run more efficient (aka not losing any health).
And I agree, a (R)estart-button would be nice. Maybe per ghost-section and the complete level.
And would've loved to see some more levels, this felt a bit short. But overall great submission!