Sound
Sound in video games can be deceptivly difficult to recreate. There are so many things that can happen depending on an enviorment. It is usually best to find those enviorments in the real world and recreate them so that it fits the enviorment the video game is taking place.
Let's say your video game is taking place in the woods. What type of sounds would you expect to hear? What time of day is it? Is it raining? Where are you located? All these factors can change to atmosphere of your world with sounds. I would expect birds chirping, tree leaves moving, howling from wolves during the night, rain drops if it's raining, or animals specifically where your game is taking place in.