Celeste: Chapter 2's B-Side Course (Red Heart)
It was not too obvious in Chapter 1's B-Side, but Chapter 2's B-Side shows that these B-Side levels will not just remix the layouts, but also repeat significant story developments that the A-Side had, if any.
For example, you start out with Madeline on her own, like, before, but after a few rooms, Badeline will show up and start chasing after her. And then even later after that, Badeline will clone herself and have them all go after you!
But then later after that, Badeline will just return back to one of herself... before just going away entirely. Chapter 2 A-Side flowed just like this, and just the same, you simply finish with Madeline on her own again.
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If you playthrough this course, that peculiar bird will show that you can jump from Dream Blocks. You just have to jump right as Madeline shoots out from the other side of them. This will give you some extra distance, and you're gonna need to know this to get through this course.
By the way, these music remixes are fantastic!