FUNDAMENTALS OF GAME DESIGN, SECOND EDITION
Point-and-Click Navigation
Aerial or context-sensitive camera models in which the player can clearly see his avatar, party, or units as well as a good deal of the surrounding environment can use point-and-click navigation. In a game with a multipresent or party-based interaction model, the player first chooses which unit or units should move (unnecessary in an avatar-based model), then in all cases the player selects a destination in the environment, and the unit or avatar moves to that location automatically using a pathfinding algorithm (an artificial intelligence technique to avoid obstacles). Typically the player can select one of two speeds: When the player selects a location, the avatar walks to it, but if he holds down a special key while selecting the location, the avatar runs rather than walks.
This technique is most often used in real-time strategy and party-based role-playing games in which many units may need to be given their own paths and the player does not have time to control them all precisely. If a unit cannot get to the location the player designated, that unit either goes as far as it can and then stops or, upon receipt of the command, warns the player that it cannot proceed to an inaccessible destination.
Using point-and-click navigation, the player can indicate precisely where he wants the unit to end up without concerning himself about avoiding obstacles, a convenience in cluttered environments where the player may not clearly see which objects actually block the path. It is also helpful in context-sensitive camera models because the player cannot always see clearly how the avatar should get from one place to another and often has no freedom to move the camera.
At times, it can be a disadvantage that the player cannot control the path that the unit takes, so allow the player to designate intermediate points, called waypoints, that the unit must pass through one by one on its way to the final destination.
Waypoints enable the player to plot a route for the unit and so exercise some control over how the units get to where they are going.
