When planning your sound design, deciding which sounds should be included in the game is often the most important place to start. This is especially true of small or simple games, particularly those with low budgets. It can be easy to get carried away with sound ideas, but it’s very important to consider the overall purpose of your game’s sound design. What do you want it to convey to the player? In other words, how do you want sound to impact the gameplay experience?
If you’re having trouble answering this question, then shift your focus to the gameplay itself. For many players, myself included, sound effects provide a very effective form of feedback. This feedback can be as simple as a bell-type sound after scoring points or picking up a coin.
If you have a variety of distinctive items that the player can pick up in the game, you’ll most likely want a unique sound effect for each one. However, in many cases you’ll still need them to sound similar in some way, to help reinforce the fact that these items all serve similar ends. For example, your game may feature different-sized coins and various colored jewels, all of which up the player’s score, by different amounts. You’ll likely want some auditory distinction for each one, but also a categorical similarity amongst them all.
In general, it’s wise to have some form of auditory feedback for anything that the player is controlling, such as running, jumping + landing, shooting, etc. This will heighten the player’s sense of control and help keep them engaged in the gameplay. Otherwise their mind may unintentionally wander, having only visual cues to guide them.
The bottom line is, you don’t need everything in your game world to make noise. This would overwhelm the player. You just need the right combination of sounds to keep the player immersed, while also conveying important information to help them understand (without having to stop and think) what’s going on.