Taking a walk can be an amazing source of inspiration for how the world works. There are plenty of things that go into creating a virtual environment–buildings, plants, people, animals–that are relatively easy to emulate because of how often you consciously make note of them. However, there are also plenty of more subtle elements like background sounds, echoes, light sources, and the general "feeling" of a place that are often more unconsciously observed. This makes them more difficult to replicate and can lead to an experience feeling fake or shallow.
The point of this exercise is to use a form of walking meditation to focus on some of the things you might not normally focus on. By consciously focusing on a certain more subtle aspect from our world, you will have a more concrete reference point when you are building a new one of your own.
Here's the basic idea: when you're walking somewhere, pick an element of your walk and try to focus on it for the entirety of your walk. Some of these take a bit of practice, so make sure your walk is at least 15 minutes long. It's also important to stick to one element per walk, at least with a new element, so that you can teach yourself to hone in on that particular kind of detail. I've included some suggestions below for elements to focus on:
Sounds
Pay attention to the sounds around you. The sound of your footsteps: wet concrete, dry concrete, leaves, snow, puddles. Cars: engines, breaks, revving, honking, screeching. Natural noises like rain, dripping or rushing water, animals in the brush, and the wind. Human noises like footsteps, talking, laughing, doors opening and closing, music.
Figure out where the sounds are coming from. Are the sounds moving? Where are they going? Can you hear the Doppler effect? Pay attention to where you're walking, of course, but focus on the sounds around you.
Sources of Light
This is more effective at night. Identify where the light is coming from: street lights, head lights from cars, open and closed windows, airplanes, traffic lights.
Watch how the light reflects or diffuses on the materials around it. Watch if the shadows are sharp or soft and how distorted they are. Watch how your surroundings change as light is introduced or removed. Watch how the color starts seeping into the area when a car's headlights come closer and how everything fades when they speed away.
Shapes of Buildings
Look at the buildings around you: houses, apartments, shops, offices, schools. How large are they? What materials are they made of? What's it shaped like; is it a giant block of material or does it have recessed areas? How do you get in: where are the doors? What do the doors look like? Are there stairs to the door? How dirty is the building; does it look like it's been around for a while? How does your perspective change as you walk by it? What does it look like in relation to the buildings around it; big, small, grand, dingy, impressive, sad, abandoned? What kind of detail can you find in the brickwork, around the doors or windows, around the roof? Is anyone entering or leaving the building? What do they look like they're there for?
The "Feeling" of Your Surroundings
Unfocus your attention. Rather than looking at a specific part of the environment in front of you, try to look at all of it. As you walk forward, how do things move in your vision in relation to each other? Can you detect the bob of your vision as you footsteps move your body up and down? Try to look at the world as if you are looking at it through a screen and take it all in at once.
Materials
What are things made of? Does the material seem new or has it been around for a while? Has it been exposed to the elements? How does light reflect off of it? How has it been combined with or attached to other materials? Does it look smooth, rough, glossy, fuzzy, prickly? Does it look heavy, light, bulky, delicate? Why would someone have picked that particular material for what it is currently being used for? Where has it broken? Where does it look like it would break? What does it feel like, smell like? When you tap it, what sound does it make?
Man-Made Artifacts
Take note of things that were clearly made by people. Vehicles: cars, buses, bicycles. Infrastructure: roads, bridges, traffic lights, bus stops, sidewalks, fences. Buildings, trash cans, toys, trash, lawn chairs. How do people in this area use their surroundings? Is there any effort to work with nature? Everything manmade was designed by someone; who made it? For what purpose? Why did they put it where they did? What sort of laws would dictate what can and cannot be in this area? What sort of unspoken rules apply to the objects?
Trash
An extension of the above suggestion and includes things like gum on the sidewalk, bits of paper, lost gloves, trash cans on the side of the road, dropped food, and things of that nature. What constitutes trash? Where has it gathered? Does it look like it was intentionally trash or has it become trash out of loss or neglect? Would you touch it? Why or why not? Does it look salvageable? Where do you think it came from? Do you think the owner misses it? What does it tell you about the owner?
Other Walkers
Warning: people don't like strangers looking at them. The point of this exercise is to learn about people in your environment, not to be a creep. Unless you want to try some variation of this meditation that involves scaring other people, don't stare at them. A cursory glance should be more than enough.
What are they wearing? What does their hair look like, if you can see their face, what sort of expression do they have? Can you imagine who they are, what they're doing, what they might be thinking about? How are they reacting to others in their environment? If there are two or more people in a group, how are they interacting?
Plants
Take note of trees, grass, flowerbeds, moss, climbing vines, weeds between the sidewalk, and other plants around you.
Where are there plants growing? Is someone clearly taking care of them or are they unmanaged? Do they seem out of control? Did someone plant this or did it grow by itself? Would you call it pretty? How old does it look? Has it been damaged? Does it seem healthy? If you could give it an emotion, which emotion would you give it?
Ugliness
What around you would you classify as "ugly"? Why? Is it the shape, color, material, consistency? Is it organic, man-made, or both? Does it stem from decay, disinterest, cheapness, or something else? Did it become ugly over time or was it always that way? What would you do to make it "better"? Can it be improved, is it a lost cause, or is it better because it is ugly? Does it fit in with its surroundings or does it stick out to you?