Complex sentence: Stealth games also emphasize the audio design when players must be able to hear the subtle sound effects that may alert enemies to their actions; noise will often vary as the player walks on different surfaces such as wood or metal.
Split into simpler sentences: Stealth games also emphasize carefully designed audio, because players must be able to hear the subtle sound effects that may alert enemies to their actions. Noise will often vary as the player walks on different surfaces such as wood or metal.