For context: I managed to platinum the entirety of the Klonoa Phantasy Reverie Series. While don't have that many problems during gameplay, Extra Vision and Chamber o' Horrors unsuprisingly caused me to panic for hours.
Bandai Namco for Klonoa and for the BGM. Edit: I forgot to mention about that one doll piece in "The Ark Revisited", cuz I literally had to grab another controller to summon Popka (2P support) ONLY to get all the dolls in the 2nd game.