On further research, I've noticed that EVERY SINGLE RESOURCE lists a different requirement.

One source says "change color three times"
another says "destroy all panels in one chain"
yet another says "change 6 geo panels colors"

can confirm that "change color three times" or "change 6 geo panels colors" are closest to being an accurate description, for anybody else in the future who may come across this. "Destroy all panels" is NOT correct.

I set up the symbols in a way that red panels turned yellow, yellow panels turned red, and red turned blue. The instant that the blue symbol, the third color change, was destroyed, the dark world level was unlocked. It was 7 panels that changed though. the 4 red ones in the front, and 3 of the yellow panels behind it. So at the very least, the number "6" is wrong, and the panel count itself is probably also wrong, leaving "change color three times" to be the accurate one.

I have no idea if it NEEDS to be in a single chain or not though. But you don't need to destroy all of them.

Sheesh, calm down, dude. People are allowed to be wrong sometimes. Especially when the requirements are weird, finicky and/or obscure, it's rather easy to be mislead into thinking you've found the "proper" way. I remember having a bit of trouble with 1-3 ("take at least 1 dmg", but IIRC the enemy has to be the one who attacks, which threw me off) and 6-4 with the prinny bowling, since the stage is slightly different after the first clear (IIRC the map is covered with No Lifting and the 12-pounder prinny is absent).

Anyhow, for 8-2, yet another author says to "create at least one geo chain", which is another possibility. I can't confirm it right now since I don't have a file with that DW stage still locked, but IIRC the way I used to do it was to destroy the "No Entry" Red geo symbol and the "No Lifting" Yellow one; Lift the remaining yellow symbol, throw it in one of the red panels and set it off. I don't think I interacted with the Blue symbols at all.

引用自 neemoos：

Sheesh, calm down, dude. People are allowed to be wrong sometimes. Especially when the requirements are weird, finicky and/or obscure, it's rather easy to be mislead into thinking you've found the "proper" way. I remember having a bit of trouble with 1-3 ("take at least 1 dmg", but IIRC the enemy has to be the one who attacks, which threw me off) and 6-4 with the prinny bowling, since the stage is slightly different after the first clear (IIRC the map is covered with No Lifting and the 12-pounder prinny is absent).

Anyhow, for 8-2, yet another author says to "create at least one geo chain", which is another possibility. I can't confirm it right now since I don't have a file with that DW stage still locked, but IIRC the way I used to do it was to destroy the "No Entry" Red geo symbol and the "No Lifting" Yellow one; Lift the remaining yellow symbol, throw it in one of the red panels and set it off. I don't think I interacted with the Blue symbols at all.

You're right. I apologize for the overly aggressive language and have edited the replies to sound better. I was just frustrated at the time.