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There are many games out there with physics interactions, but usually those are small games with controlled environments.
Zelda has a big scope, which makes things much more difficult to design.
“The most complicated part of game development is when different systems and features start touching each other,” said
Shayna Moon, a technical producer who’s worked on games like the 2018
God of War reboot and its sequel,
God of War: Ragnarök, to Polygon. “It’s really impressive. The amount of dynamic objects is why there are so many different kinds of solutions to this puzzle in particular. There are so many ways this could break.”
Moon pointed toward the individual segments of the bridge that operate independently. Then there’s the lava, the cart, and the fact you can use Link’s Ultrahand ability to tie any of these things together — even the bridge back onto itself.
Nintendo reportedly used a full year of
Tears of the Kingdom’s development for polish, and it shows. “The amount of different options available is a testament to the amount of work that every single person at every level of the team did, especially the QA testers,” Moon said. “Open-world games with a ton of real-time physics objects like this are notoriously difficult to QA test.”
Software engineer Cole Wardell put it another way: “Imagine the lava bridge above, when you grab the end of it, you pull part of it to one side,” he said. “Well, now that drags the other attached piece a little bit with it, and that piece moving makes the next piece move, and so on and so forth. And if any one element of the track collides with something, it has to be nudged or slid back into somewhere that doesn’t collide, which moves the pieces next to it which moves the pieces next to it.”
Tears of the Kingdom also has its own rope-like physics flex:
Another viral clip showed a door opening using four wheels and a chain. That’s a complex interaction that takes no shortcuts, Wardell told Polygon. “As a rule, physics engines take a lot of shortcuts and make a lot of assumptions, both for optimization purposes and to keep developers from pulling their own hair out,” Wardell said. “Almost all of these shortcuts, whether it be collision-free ropes [or] rotating objects only applying forces in specific ways, would make this kind of mechanism flat-out not work, or the chain start vibrating until it disappears from view in a single frame, or some other infamous physics glitch.”
He said that rope bugs “vibrating out of control” are so common because of these problems. “If you don’t do everything
just right, one movement will cause the other parts of the rope to move, and their movement will cause more collisions — God forbid you want the rope to collide with itself. Those collisions will cause more nudges, which is more movement, which ends up with your robe vibrating out of the map.”
Doshi explained that complex physics are common in games, but said that
Tears of the Kingdom pushes the limits of its engine to create exceptional gameplay and puzzles. “Realistic physics simulations take hours to do calculations to make sure it is highly precise and accurate,” he said. “Game physics needs to produce similar results every 16-32 milliseconds (60-30 frames per second).”
Some games are able to avoid these complexities by designing around them, Doshi said. That means restricting player action, which is the antithesis of
Tears of the Kingdom’s design. There are constraints, but somehow, in this game, it still feels like nothing is off-limits.
“In game development, it’s not
if physics will break down but
when,” Gravity Well senior engineer and former Call of Duty developer
Josh Caratelli told Polygon. That’s why there’s
a whole Reddit page about physics goofs — player characters ragdolling into oblivion or enemies bouncing off the walls. It’s not that games with physics bugs or glitches are poorly made; it’s just really easy for things to go wrong.
“What’s extremely technically impressive is how stable it is and how it all fits together in a way where there’s no pre-programmed solution and players can solve puzzles with complete freedom,” Caratelli added.
Moon noted that it’s not exactly that other studios can’t reach this level of technical innovation, but that they don’t prioritize the resources needed to do it. Often, that comes down to supporting the humans who make the games we play.
Tears of the Kingdom was seemingly built on top of
Breath of the Wild, reportedly with a large portion of the same team working on it.
“IF YOU WANT GOOD GAMES, YOU HAVE TO GIVE A DAMN ABOUT THE PEOPLE MAKING THEM”
“There is a problem within the games industry where we don’t value institutional knowledge,” Moon said. “Companies will prioritize bringing someone from outside rather than keeping their junior or mid-level developers and training them up. We are shooting ourselves in the foot by not valuing that institutional knowledge. You can really see it in
Tears of the Kingdom. It’s an advancement of what made
Breath of the Wild special.”
According to Moon, it’s increasingly common for game developers to feel like they’re holding some feature or another together with duct tape, figuratively speaking, after the person who originally spearheaded its design got laid off or left; there’s a lot of time wasted reconfiguring and assessing how something was done. It’s not that Nintendo doesn’t have its own problems, because it certainly does —
Nintendo of America QA testers spoke out about a “frat house” experience within Nintendo of America’s Washington headquarters last year, for instance. But the company does appear to value the expertise of its development staff.
“In addition to the overall hard work of the team, the institutional knowledge is clearly a factor in why this ended up being so smoothly done,” Moon said. “The more stable and happy people are, the more they are able to make games of this quality. If you want good games, you have to give a damn about the people making them.”