Just wanted to touch on the subject of changing one's unspoken/unwritten lore of a story.

An example would be my own series, and this might be heavy spoilers for the future..
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I had a hard and fast rule that the four “beasts” were unkillable, they old would die if the universe ends, then it became they will die of old age and the “title” will be passed on, before it became each child born of them would have the same abilities as them.

Along with this I kind of found a way possible to “kill” the main characters, which barely averted by chance but the stakes are still there.

I did not plan for this, and would had hated it when I first started my comic but found it extremely interesting because it lead to one main character to go through extreme changes.

Another change was the creatures known as Deadsiders, which were just going to be annoying ghost and spirits that can “die” and be sent back to their world but now are going to be very important as one (or two) is a major character now.

Also their was going to be “half” deadsiders, basically like half demon status but now as it stands if one parent is a deadsider the kid will be one too.

That's the best example I got right now, but what is your changes to the backstage of your world?

Uno online? What kind of desperado plays Uno online?

A spammy desperado

A gone desperado, thanks to Amelius