MMORPGs are usually based on the concept of a perpetual world. You make your character and enter a large world filled with cities, people (both other players and NPCs), and all sorts of intrigue. You can fight monsters, undertake tasks given by NPCs, and participate in many events. Exceptions to these rules are rare and usually gimmicky. See also An Adventurer Is You, Heroic Mime, and Status Quo Is God. This could be considered an Acceptable Break From Reality, given that it's pretty much necessary for the genre. For non-MMORPG examples, compare Medieval Stasis and Modern Stasis.