The mechanics of a game are the “brain” of a game's design. Whenever the player wishes to perform an action, he must invoke one of the available verbs in the given game state (more on this in the next section). Then his input is processed internally by a set or rules and an output is given (hopefully being what the player had intended to do). Game mechanics must be designed to be the gears that spin under the hood; all the player must do is step on the gas and feel the car moving. He does not need to understand how the engine works to be able to drive.
The game designer, however, must have a clear and detailed definition of such mechanics, in order to provide the other developers with an accurate picture of the desired outcome in the game. The most important component of the mechanics layer is the definition of the process in which verbs (the layer downwards) are manipulated by the system and provide feedback, both to the player and to the game world, of the actions performed, thus bringing the desired game features and content (the layer upwards) to life.
The maximum power available can be reduced if the player keeps hanging on things or executing other tiring actions -- thus, consuming power slowly -- and with every consecutive blow struck upon the giant. Pressing the button once willl start filling up the circle with power; pressing it a second time will unleash a blow as powerful as the current power level in the circle. The player then has to wait a short while in order to recover this power. As the player sees it, the character just gets tired of those extreme actions; he cannot use his full power to strike all the time, and needs to stop to rest for a little bit.
Gilliard: And now how am I supposed to take down this giant beast?
Rafael: Well, that bow in your hands should be useful for something...
Gilliard: Yeah... That makes him MUCH smaller...
This layer consists of the actions that will be performed by the player during the game. These actions mean the desire of the player being enforced upon the game as low-level micro-decisions that will use the mechanics layer to run the player through his game experience. Some of these verbs might be “shoot”, “jump”, “brake”, or even “change camera perspective”, “craft an item” and “move units”.
Verbs are related to specific game states, that define which verbs are available to the player at any given moment. For example, if “in car” is a game state for Grand Theft Auto, “accelerate” and “brake” might be some of the available game verbs, as “shoot” and “reload” would be verbs for the “weapon drawn” game state. A picture showing a simple example of game states and their corresponding verbs in the Grand Theft Auto universe is provided below:
Game states and their respective verbs are related to a cognitive process representing an important aspect of games: learning. While specifying game verbs, the designer has to make sure that their use and relations with any game state thereafter is coherent throughout the entire game. Designers must take what the players learn very seriously and must not expect them to act against it. For example, if in a given game state the player is not allowed to shoot while inside a car, and suddenly, in another state, he is allowed to do that (or worse, he is required to do so to get through a given obstacle), the transition between such states must be made clear through the appropriate feedback.
Gilliard: There are so many verbs I can use in this game! I can walk, jump, drive, buy things...
Rafael: OK, here's some verbs for you: stop talking and shoot!