Core Mechanics - Fundamentals of Game Design - page 310

ACTIVE CHALLENGES
Suppose that the level designers want to set up a more complex challenge for the
player, such as a puzzle that the player manipulates to unlock a door. Your design
for the core mechanics must supply the level designers with the necessary entities
and mechanics to define the puzzle, allow the player to interact with it, display the
consequences of her actions, and detect when the puzzle has reached its solution
state. This is an active challenge .

NOTE Active
challenges require
mechanics that imple-
ment their activity.

An enemy character that the player must defeat in combat represents another
active challenge. The core mechanics define the characteristics and the AI of the
enemy character. The level designers place that character at a location in the land-
scape by setting his location attributes and perhaps they also set some other
attributes, such as health and ammunition. In effect, your design creates the tools
and parts that the level designers use to build levels, create puzzles, position ene-
mies, and so on. In a long game, the level designers probably reuse the same tools
several times to create variants of the same challenge in different parts of the game.
(This is one of the reasons why the same characters seem to appear over and over
in a game: The level designers reuse the basic mechanics.)

Actions and the Core Mechanics
The challenges in a game vary from level to level in type, frequency, sequence, and
other respects, but the actions available to the player normally do not change from
level to level except that, in some games, more actions become available as the
player progresses through the game. Consequently, the level designers play a
smaller role in determining what actions are available than they do in choosing
challenges for a level, though they can choose challenges that tend to require the
use of some actions more than others. (Sometimes level designers also specify that
familiar actions should not be available. See “Make Atypical Levels Optional” in
Chapter 12.)

PLAYER ACTIONS TRIGGER MECHANICS
When you design the core mechanics, you must specify a mechanic that imple-
ments each action in each gameplay mode, which will either initiate an event or
start or stop a process. When the user interface detects data arriving from an input
device, UI routines determine what action the player desires by checking the
assignment of actions to buttons (or similar control devices) established by the
gameplay mode's interaction model. The UI then triggers whatever mechanic you
specified for that action.

Let's look at a simple example from a first-person game. When a player presses a
button assigned to the crouch action, the UI triggers a crouch mechanic that imple-
ments the action. You must define this mechanic to do two things. First, it changes
a symbolic posture attribute of the avatar from the walking upright state to the