It was the 20-year anniversary of Halo 2 at the weekend, which saw the shooter’s modern counterparts celebrating with classic multiplayer maps and long-lost levels. But also emerging from the dust of time are insights to the sequel’s development back in 2004. Rolling Stone interviewed two key designers of the game and made a fun discovery. The Flood (the sickly pale alien infestation that briefly turns Halo into sci-fi horror) was partly inspired by a colourful and innocent children’s book about a nice elephant.