"All Chapters" includes every a, b, and c side for chapters 1-8 as well as farewell.
"True ending" simply involves unlocking and completing farewell, which doesn't require b-sides or c-sides, although players will sometimes route 5b and 6b into runs because they're faster and also collect 2 of the 4 hearts needed for getting into core.
The heart gate in chapter 9 is skippable so the B-sides and extra crystal hearts are unnecessary, but the gate in core is not skippable so you still need 4 crystal hearts (plus obv the one at the end of core to unlock chapter 9).
Everest had one of the biggest updates so far with Everest Core becoming the "Stable" version. Here is what you need to know as a player and what rule changes are happening:
To put it in layman's terms, they're updating the game to use a newer framework. Which
