In this chapter, alternate reality games (ARGs) are examined as an example of immersive and pervasive play, in which game play may escape a proscribed sphere and permeate into "ordinary", non-ludic life. Particular attention is addressed to this genre of games' dissimulative, "this is not a game" rhetoric, which seemed to early critics to promise (or threaten) a compelling engagement with a deviously simulated reality. Using the 2007 game World Without Oil as a case study, the chapter examines the potential for ARGs to blur the boundaries between in- and out-of-game realities in a practical sense without resorting to the sort of seamless simulation or requiring the naive reception that early criticisms assumed were features of play.