Games and other media often allow consumers to get 'sucked in' by an experience and forget the happenings of the real world. In Mood Management Theory, absorption potential measures the media's ability to interfere with the consumer's current mood preserving processes. High absorption potential supports mood alteration but can undermine mood preservation, both depending on mood alignment.
As often cited, games as a medium ask consumers to be more active than other media. While other media can boost absorption potential by inviting consumers to parse non-obvious messages and imagery, the definitive interactivity in games provides a unique layer of audience participation that persists through the entire experience.
Bowman and Tamborini refer to task demand as a measure of a piece of media's cognitive requirement of the consumer. They showed that raising the task demand of an otherwise unchanging game, led to increased mood repair among initially bored participants in a lab setting. Participants who were stressed before the gameplay did not show a strong preference towards either low or high task demand, but did appear less stressed after playing. Finally it was noted that a threshold exists in which in-game task demand becomes overwhelming or frustrating, leading to a decrease in mood repair (Bowman 2012).
World of Warcraft absorbs players by offering lines of quests that never seem to end and smaller goals that always give the player something to do. When player complete one goal there is almost certainly a group of goals to be attempted next, leading to a 'just one more quest' mentality. There is an enormous amount of content in this game, and players attempting to escape into the game's world for an extended period of time encouraged to. The ability to interact a multitude of players allows players to become absorbed in the game, through little more than the text chat window (and maybe a dancing avatar).
At its core, Tetris is very simple, but it has an exceptionally high absorption potential. Players have a great deal of control over how the game unfolds, and with proper planning can exhibit competence. Players who are not yet skilled at the game can access easy levels that allow them to overcome less complex situations than advanced players would, minimizing the game's potential of boring or stressing players. Whether it happens in the first couple blocks or the first couple levels, players often get lost in this game and end up in a strong state of flow. As an abstract game, Tetris also has a very low mood alignment helping players divorce themselves from the world that has introduced their potentially noxious mood.
This is an industry standard and is empirically validated
Bowman ND and Tamborini R (2012) Task demand and mood repair: the intervention potential of computer games. New Media & Society 14(8): 1339–1357.
Zillmann, D. (1988a). Mood management through communication choices. Am. Behav. Sci. 31, 327–341.