Audio Effect

We like the audio effect of Mini Metro. That game has an extremely abstract visual art style, and it heavily relies on sound effects to sense the heavy traffic that is occurring in the metro system the player designed.

In this game we plan to do something similar. Whenever something happens in the game, a short auditory cue will be played in the background. Another example is changing the background music to a faster melody when the timer of a stage is below 30 seconds. The more significant the event is, the lengthier and louder the cue will be. When a well-designed terminal operates smoothly, the small auditory cues will come together and sound pleasing to the ears. This encourages player to build a better terminal, and provide implicit feedbacks to the player when something goes right or wrong.

The sounds and background music are toggle-able through the options menu.

The audio effects vary in the following aspects:
 * Tone
 * Most events in-game can be roughly classified into "positive" or "negative". For example, a trucking receiving the container it has been waiting for, or a container is put onto the ground from a ship by the crane are considered to be "positive" while a truck waiting near a stack for too long is considered to be "negative". Audio effect for positive events will be naturally more pleasing to the ears, while those for negative events will be relatively more disturbing sounds like truck-horn.
 * Volume
 * More significant events will come with a sound with higher volume, and vice versa. A truck successfully picking up its container is by nature much less significant than a ship finishing its cargo transfer, so the sound for the later will be much louder than the sound of the first one. However even the loudest sound would still be considered low-volume, since they reinforce the playing experience from the side, and are not the main experience themselves.
 * Duration
 * Similar to the previous point, sounds of events that happen frequently should die down very soon, while sounds of events that happen infrequently should only die down after a long time.