Why Tears of the Kingdom’s bridge physics have game developers wowed

There is a bridge to cross the lava pit The Legend of Zelda: Tears of the Kingdom‘s Marakuguc Shrine, but it’s broken. More than half of the bridge is stacked on itself on one side of the pit, with a truncated segment on the other. The bridge is the obvious choice for crossing the lava, but how do you fix it?

A clip showing a possible solution went viral on Twitter shortly after Tears of the Kingdom‘s release: The player uses Link’s Ultrahand ability to unfold the stacked bridge by attaching it to a mobile platform in the lava. When the mobile platform – now attached to the edge of the bridge – activates and moves forward, it pulls the bridge taut, spewing lava, until the suspension bridge is actually suspended and can be crossed. But it wasn’t the solution itself that appealed to the players; instead, the clip had the game developers’ jaws on the ground, in awe of how Nintendo’s team struggled to make the game’s physics system do That.

For players it’s just a bridge, but for game developers it’s a miracle.

“The most complicated part of game development is when different systems and functions start to collide,” he said Shayna Moona tech producer who has worked on games like the 2018 God of war reboot and the sequel, God of War: Ragnarok, to Polygon. “It’s really impressive. The amount of dynamic objects is why there are so many different types of solutions for this puzzle in particular. There are so many ways this can break.

Maan pointed to the separate segments of the bridge that work independently of each other. Then there’s the lava, the cart, and the fact that you can use Link’s Ultrahand ability to tie all these things together – even the bridge back on itself.

Nintendo has reportedly used an entire year Tears of the Kingdom‘s development for Polish, and it shows. “The number of different options available is a testament to the amount of work each person at every level of the team has put in, 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.”

Another big game that inspired this kind of physics based shock and awe from game developers on social media was in 2020 when The last of us part 2 including a rope needed to solve a puzzle. Like it Tears of the KingdomThe bridge, the rope and its natural-looking movements were just something players expected to work, but game developers could see the amount of work that went into developing it.

The bridge has a lot of different points that pull together within the physics system, said Luna Nielsen, a software engineer who visits Luna the fox girl online and live streams about the complexity of game engines. “It gets into some pretty mathematical stuff. Things can get really funky when something pulls a little too much, and suddenly the bridge is in on itself. So it has to come out. And then one thing has gone too far back. It’s starting to get really bad, because [the pieces of the bridge] are essentially different from each other’s movements.”

Software engineer Cole Wardell put it another way: “Imagine the lava bridge above, if you grab the end of it, you pull part of it aside,” he said. “Well, that kind of drags the other attached piece along, and that moving piece makes the next piece move, and so on and so forth. And if an element of the track collides with something, it must be pushed or pushed back to a spot where it will not collide, which will move the pieces next to it, which will move the pieces next to it.

“The last time I saw something so impressive in terms of physics/gameplay, the rope was in The last of us part 2. And the rope just came in [a] few highly controlled scenarios,” said Rocksteady Games senior gameplay and combat programmer Aadit Doshi on Twitter. “It’s awe-inspiring to be able to confidently present the player with a stack of blocks connected by chains that move in precise ways, without clipping, without objects shaking like crazy as it tries to figure out what to do.”

Tears of the Kingdom also has its own rope-like physics flex: Another viral clip showed a doorway using four wheels and a chain. That’s a complex interaction that doesn’t require any 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 prevent developers from pulling their own hair out,” said Wardell. “Almost all of these shortcuts, whether it’s collision-free ropes [or] rotating objects that only exert forces in specific ways would cause these types of mechanisms to fail, or the chain to start vibrating until it disappears from view in a single frame, or some other notorious physics flaw.

He said rope bugs that “get out of control” are so common because of these issues. ‘If you don’t do everything just now 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 crash into itself. Those collisions will cause more nudging, which is more movement, which will cause your robe to vibrate out of the map.

explained Doshi that complex physics is common in games, but said so 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 they are very precise and accurate,” he said. “Game physics should produce similar results every 16-32 milliseconds (60-30 frames per second).”

Some games can avoid this complexity by designing around it, Doshi said. That means limiting the player’s action, which is the antithesis of Tears of the Kingdom‘s design. There are restrictions, but somehow in this game it still feels like nothing is off limits.

“In game development, that’s not the case if physics will break down, but whenGravity Well senior engineer and former Call of Duty developer Josh Carrelli said Polygon. That’s why there is an entire Reddit page about physics blunders – player characters falling 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.

However, Caratelli emphasized that Tears of the KingdomThe physics of ‘s is not magic – it is clear that Nintendo has a great understanding of the physics interactions in the game. “What’s extremely impressive technically 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 in complete freedom,” added Caratelli.

Moon noted that it’s not exactly that other studios can’t achieve this level of technical innovation, but that they don’t prioritize the resources required to do so. Often that comes down to supporting the people who make the games we play. Tears of the Kingdom was seemingly built on top of Breath of the Wildreportedly with much of the same team working on it.

“There’s a problem within the gaming industry where we don’t value institutional knowledge,” Moon said. “Companies will prioritize bringing in someone from the outside rather than retaining and training their junior or mid-level developers. We are shooting ourselves in the foot by not appreciating that institutional knowledge. You really see it Tears of the Kingdom. It is an advancement of what has been made Breath of the Wild special.”

According to Moon, it’s increasingly common for game developers to feel like they’re holding some feature together with duct tape, figuratively speaking, after the person who originally ran the design was fired or left; a lot of time is wasted reconfiguring and reviewing how something was done. It’s not that Nintendo doesn’t have its own problems, because it certainly has – Nintendo of America QA testers for example, spoke out last year about a “frat house” experience at Nintendo of America’s headquarters in Washington. But the company does seem to value the expertise of its development staff.

“In addition to the team’s overall hard work, the institutional knowledge is clearly a factor in why this ultimately worked out so smoothly,” said Moon. “The more stable and happier people are, the better they can make games of this quality. If you want good games, you have to give a damn about the people who make them.”