I didn't finish Farewell too - in my head, I consider that optional as it was added later and has a significant difficulty bump - the devs knew that too as they gated it.

Exactly what I thought when I saw this. The Celeste soundtrack is so good - I'm not good at platform games but the music kept me going. The story was great too, but I'm not sure I would've stuck with the game if the first steps (see what I did there?) didn't have me humming along.