The mechanism by which the player controls the movement of the player-character through the game world. The most common style is compass navigation.
One oft-discussed alternative is relative navigation, in which the player uses commands like RIGHT, LEFT, FORWARD, and BACK, whose meaning changes depending on which way the player-character is facing. (That is, going forward is not the same as turning left and then going forward.) Battlestar, an early (ca. 1979) UNIX game used this system.
Another possibility is named navigation, where the player indicates his intended destination with a descriptive name in a command such as GO TO KITCHEN (or perhaps simply KITCHEN).
- Discussions about navigation on the rec.arts.int-fiction newsgroup