These are the Rules for a Proper Mystery; all good mysteries must follow these rules in order to be 'solvable' by the audience.
The Game Masters' Riddles and the Solutions must follow these.
The Umineko DecalogueEdit
It is forbidden for the culprit to be anyone not mentioned in the early part of the story.
It is forbidden for supernatural agencies to be employed as a detective technique, unless it is already part of the riddle.
It is forbidden for hidden passages to exist.
It is forbidden for unknown drugs or hard to understand scientific devices to be used.
(not included) It is forbidden for stereotypical minorities to assist or hinder the detective beyond providing their own conclusions and interpretations, or for said minorities to be the culprit. (possible re-interpretation of the original Knox's 5th, with the part in bold added to avoid contradicting Knox's 9th.)
It is forbidden for accident or intuition to be employed as a detective technique.
It is forbidden for the detective to be the culprit.
It is forbidden for the case to be resolved with clues that are not presented.
It is permitted for observers to let their own conclusions and interpretations be heard.
It is forbidden for a character to disguise themselves as another without any clues.