While Game of the Year discussions are still ongoing, you’re sure to see The Legend of Zelda: Breath of the Wild near the top of many people’s lists. BotW feels like a living, immersive world, and a lot of that comes down to how the game handles interactions between its many moving parts. Those who’ve played the game must have been amazed at least once by its meticulous attention to detail combined with multiple, interlaced systems that allow for some absolutely unique gameplay moments.

It’s the grounded nature of BotW’s environment that makes the fantasy elements so compelling. Most everything in the game, including physical objects and the weather, behaves more or less as you’d expect it to in the real world. It’s easy to imagine Hyrule existing in our world when you take a moment to watch grass waving in the breeze, see an apple roll downhill, or notice clouds drifting lazily across the sky.

The credit for this has to go to the programmers at Nintendo, who combined lots of different systems into a single enthralling play experience. Twitter user @Brainchildlight is an expert in practical aspects of lighting and particles, and has been documenting the technical tricks used to help give Breath of the Wild such a realistic playspace. Their findings were collected in an article published on ResetEra a few days ago. The article goes deep, deep into the technical aspects of Breath of the Wild’s lighting, so if you’d like a more in-depth analysis, please don’t hesitate to follow that link. For those with a more casual interest in the subject, we’ll highlight a few examples of Brainchild’s findings further down.

Lighting demonstrations

#BreathoftheWild A better look at SSS. As more sunlight illuminates these plants, the brightness/color of their undersides change. pic.twitter.com/pykKyITNlk — brainchild (@brainchildlight) November 27, 2017

Sub-surface scattering (SSS) is used in situations where an object isn’t entirely opaque, but isn’t entirely transparent either. It’s used here to show sunlight shining through a leaf with different intensity during different times of day, and elsewhere to simulate light shining through the canvas of a tent. When daylight comes, the fabric doesn’t show any light coming through, implying the lights inside have been blown out. You probably wouldn’t notice things like this unless you were looking for them, but they all contribute to making the world feel like a more authentic, natural environment.

#BreathoftheWild High gloss materials are the only materials w/enough specular reflectivity to reflect Link, and only found in shrines :( pic.twitter.com/TBaLgKgBC9 — brainchild (@brainchildlight) November 28, 2017

Full reflections are pretty uncommon in Breath of the Wild, but the engine is capable of rendering them. Quite impressive for a Wii U game! Nobody in Hyrule has a mirror, but Link can still see what he looks like if he gets close to a wall or metal surface in one of the land’s many shrines. Water reflections can be gorgeous, but aren’t nearly as detailed.

#BreathoftheWild Elemental weapons are emissive and act as area lights. Their luminosity is also factored into the reflectance of materials pic.twitter.com/4G3j18Hgy7 — brainchild (@brainchildlight) November 10, 2017

Some weapons and other items act as their own light sources, especially those with elemental properties. Breath of the Wild’s lighting engine keeps track of the glow from Link’s inventory and projects it on whatever’s around him in real time. The same is done with particles flying through the air, whether those are embers, snow, or fireflies. Each type of particle has its own behavior and will react to solid objects by trying to avoid them rather than passing straight through.

Weather

#BreathoftheWild Environment physics and cloud propagation are both tied to a wind simulation system. pic.twitter.com/c1marArF3a — brainchild (@brainchildlight) November 10, 2017

As you might expect based on the title, Breath of the Wild has some pretty robust systems in place to track the movement of the wind. Fog, clouds and grass follow the wind wherever it goes, and this also affects the particles mentioned above. The game determines whether an object should be moved by the wind based on its weight, so lighter objects like your bombs can be affected as well. Clouds are particularly interesting; since they’re procedurally generated, no two cloud banks are ever the same. Clouds don’t fully block the sun, but the game calculates how much less bright the environment should be based on current cloud cover and adjusts the intensity of the sun accordingly. We’ve come a long way since reusing the bush sprite as a cloud in Super Mario Brothers.

#BreathoftheWild Each lighting strike is a distinct directional light source. All shadow casters prioritize shadows to nearest strike. pic.twitter.com/yy7br5eifN — brainchild (@brainchildlight) November 25, 2017

Lightning storms in Hyrule happen more frequently than you might expect, but some of that can be attributed to the misalignment of the Divine Beasts. When a bolt of lightning strikes the earth, it sort of acts like a new sun for a second and causes objects to cast shadows away from the flash’s source. It’s a little harder to tell where the shadow ends up when you get hit by the lightning yourself, of course.

#BreathoftheWild Water basins 'fill', 'evaporate', and 'foam' by raising and lowering the water plane below the terrain w/layered materials pic.twitter.com/LWsVNNCYlR — brainchild (@brainchildlight) November 25, 2017

Rain makes Breath of the Wild a lot less fun since it makes rock faces slippery and much harder to climb. If you’re near a flat surface though, you might notice that natural water basins start to collect water as a storm goes on for a while. This effect is achieved by altering the depth of the world’s water table temporarily during a storm. Sometimes enough water pools together that Link can use Cryonis in places he wouldn’t normally be able to.

#BreathoftheWild The game reverses this process at the end of a storm. pic.twitter.com/yu9K8ap5go — brainchild (@brainchildlight) November 25, 2017

When the storm ends, the water table returns to normal, and the flood waters appear to recede back into the earth.

#BreathoftheWild Rainbows typically only appear during the same physical conditions as real life, which is a nice attention to detail! pic.twitter.com/T2CnH7p3in — brainchild (@brainchildlight) November 29, 2017

The next time you’re caught in a storm, try checking the sky as it ends. If a rainstorm ends when the sun is out, you’ll probably find a rainbow somewhere. It’s even possible to view a rare double rainbow if conditions are just right. So intense, so bright, all the way across the sky.

As you can see, there’s a lot that goes into making Breath of the Wild feel as natural as it does. It’s worth checking out Brainchild’s Twitter page if you’re interested in this technical study. There’s lots more Breath of the Wild examination, and Brainchild has taken a look at some of Super Mario Odyssey’s stages as well.