i would argue that, as a DLC, this would be better called "epilogue" rather than "chapter 9". i started to play celeste about a month ago and, by then, i didn't know chapter 9 was a DLC. after finishing the A-sides i immediately got into chapter 9, unaware of its crushing difficulty and the advanced movement (taught in the B and C-sides of the game). it made me feel so frustrated i couldn't do it because it left me feeling really incomplete. story wise i also think it would make more sense if this was an epilogue. other than that, i think it's a spectacular (and very long and difficult) chapter of this magnificent game.