The Book of General Ignorance round differs, in particular during the Christmas specials. During the course of the "B" Series special, Fry and Davies swapped places for "General Ignorance", with Fry attempting to answer questions ostensibly written by Davies to stump him. During "D"s Christmas Special, all the "GI" questions revolved around saints. "The Book of General Ignorance" contains a list of 230 questions, most of which previously appeared in episodes of "QI". Each question explains the correct answer, and usually attempts to show why people tend to make the wrong assumptions, or believe certain myths. Each book contains two forewords, one by Fry, the
Agatha Christie: And Then There Were None to twelve items. New items go into the first available slot, and these items can be combined or examined throughout the game. The game's cursor is context-sensitive, and changes into a rotating gear when held over an item the player can interact with and use. "And Then There Were None" features a 2.5D graphics engine, which combines pre-rendered backgrounds with 3D-modelled characters. "And Then There Were None" is divided into 10 chapters. After completing a certain trigger event, the next chapter begins. The developers ensured that nothing essential to the game could be missed during the player's progression, although large