Kagu name "Rhynochetos", and the clade name Rhynochetidae, are derived from the Greek "rhis" meaning nose and "chetos" meaning corn, referring to the corn-shaped flaps over the nostrils. The specific name "jubatus" is derived from the Latin "iabatus" meaning crested. The name kagu is derived from the Melanesian names for the species. The species is variously known as the "kavu" or "kagou" in the Kanak languages, and as the "cagou" in French (also used as an alternative spelling in English). The kagu is a ground-living bird, in length. The weight can vary considerably by individual and by season, ranging from .
Creature of Havoc to the rules given the story circumstances: damage to the creature (the player) is reduced by 1 STAMINA point due to its tough hide, while rolling a double on the dice when determining the player's attack strength will instantly kill an enemy. The player begins the adventure as the "creature of havoc" of the title, an unidentified, violent beast with no concept of who or where they are. Because the creature cannot make its own decisions, it is governed by instinct, and die rolls are initially used to determine which pages to turn to, rather than the player's own choice.