Miyamoto's guiding design philosophy was to include more details than earlier games, using the Nintendo 64's power to feature "all the emotions of the characters". He likened the game's style to a 3D interactive cartoon. Some details were inspired by the developers' personal lives; for example, the Boos are based on assistant director Takashi Tezuka's wife, who, as Miyamoto explained, "is very quiet normally, but one day she exploded, maddened by all the time Tezuka spent at work." In the game, the Boos shrink when Mario looks at them, but when he turns away, they grow large and menacing.