I don’t know how to understand your comment. The goal of Slay the Spire is to climb all the way to the heart while picking cards and beating it, preferably on A20 - all the other difficulty levels being basically a tutorial leading to the real game. There is no moment involving all the players of the world and the game is generally very slow so I’m a bit lost.

I swear I remember that when you get to the heart, you get to see something like "you need [huge number] of total damage, damage that has been applied [medium number gets increased by your measly tiny damage]" or maybe "health left [huge non-round number gets decreased by very little]" and then your character dies

I just assumed that it's some online thing where it counts total damage from everyone to finally slay that heart "together"

You get your score shown as damage once you beat the act 3 boss(es) and then go on to act 4 to fight the final boss if you properly collected the three keys which unlock it while climbing.