FUNDAMENTALS OF GAME DESIGN, SECOND EDITION
Context-Sensitive Interfaces
A context-sensitive interface reduces complexity by showing the player only the options that she may actually use at the moment. Menu options that make no sense in the current context simply do not display. Microsoft Windows takes a middle path, continuing to show unavailable menu options in gray, while active menu items display in black. This reduces the user's confusion somewhat because she doesn't wonder why an option that she saw a few minutes ago has disappeared.
Graphic adventures, role-playing games, and other mouse-controlled games often use a context-sensitive pointer. The pointer changes form when pointed at an object with which it can interact. When pointing to a tree, for instance, it may change to the shape of an axe to indicate that pressing the mouse button will cause the tree to be cut down. The player learns the various things the mouse can do by pointing it at different objects in the game world and seeing how it changes.
