Rich Wilde and the Book of Dead is a five-reel Egyptian slot centred on a special expanding symbol. Three scatters trigger ten free spins, and one ordinary symbol is chosen for expansion throughout that sequence. When it can produce an additional win, that symbol fills its reel and is evaluated without requiring its expanded reels to be adjacent. Further qualifying scatters retrigger spins. This is the original Book of Dead format; the later GO Collect edition's coin vault should not be added to its rules.
To compare related slots formats, read the rules of Boat Bonanza and Ankh of Anubis Awakening.
The library also explains the difference between lines, ways and clusters to help put these mechanics in context.
Source: published game information.
