The producer of Umineko is a group called 07th Expansion. It's a murder-mystery divided into 8 parts. Each part is a repeat of the previous part, but there are slight changes introduced into each part. The basic struggle, after the whodunit question, is the argument between magic and not-magic.
The reader/watcher is assisted by three things called Truths.
Red Truth is absolute, but subjective. It can be presented without supporting evidence, but since it is subjective, there can be multiple interpretations. The Witch Side uses the Red Truth. For example:
You are not Ushiromiya Asumu's son.
The Blue Truth can be used by both Humans and Witches. If the Red Truth is a single-shot handgun, the Blue Truth is a shotgun. It can be used against both Humans and Witches, and it can counter the logic of the Witch/Human while also abiding by the Red Truth. For example:
The one who is qualified to be Beato's opponent is 'Kinzo's grandson Ushiromiya Battler', and whether you are 'Asumu's son' or not is no problem. Thus, even if you are not Asumu's son, you can be Kinzo's grandson. As long as you are Rudolf's son!There is the Gold Truth, but it doesn't play much of a role in the game. Another tool is the Purple Declaration. This appears in the last part of the game, Twilight of the Golden Witch. It is a bit of a double-edged knife, since it is used by the survivors. Only the culprit can lie while using the Purple Declaration, and it holds the same weight as the Red Truth.