Narrative - Designing Games - page 97

Games use a variety of devices to enforce story ordering:
Levels are the classic story-ordering device. Players play the first level
to completion, then the second, then the third, and so on. It's old, it's
simple, and it works.
Quests are another classic story-ordering device. A quest is a self-
contained mini-story embedded in a larger, unordered world. The world
might span an entire continent while a quest might cover the player help-
ing one shopkeeper rid himself of an extortionist. The quest starts when
the player meets the shopkeeper and hears his plight. The player then
finds the mobster, convinces him to stop or beats him up, and finally re-
turns to the shopkeeper to get paid. Within this sequence, the order of
events is fixed. But this mini-story could be started and finished at any
time as the player explores the city. And it can be suspended: the player
might meet the shopkeeper, beat up the mobster, then get distracted and
go slay a dragon in another part of the world before finally returning to the
shopkeeper to get his reward.
A third basic story-ordering device is the blockage . The simplest block-
age is a locked door. The player encounters the door, and he must go find
the key before progressing. So whatever happens while he's acquiring
the key is guaranteed to occur before whatever happens beyond the door.
Blockages don't have to literally be locked doors either; perhaps a guard
won't let you past until you go do him a favor, or a security camera will spot
and stop you unless you first go turn off the lights.
There are also softer story-ordering devices. These devices encourage
an order to the story without absolutely guaranteeing it.
Skill gating is a soft story-ordering device. With skill gating, players can
access all the content in the game from the first moment of play. However,
some of the content requires the player to exercise skill before it can be
accessed. To talk to a character, for example, the player might first have to
defeat him in combat. Players end up experiencing the content in rough
order as they progress along the skill range, even though all the content is
technically available from the start.
A version of skill gating is used in many massively multiplayer RPGs.
The player can technically go anywhere from the start, except that he
doesn't have the skill, character upgrades, or allies necessary to survive far
outside his starting area. So the game has the feeling of a massive open
world, while still gently directing new players through a carefully designed
sequence of introductory challenges.