Alí Torín

Nintendo's lead physics engineer saw the prototype that became Tears of the Kingdom and said "are we really doing this?!" Then they did it. That's why players can build working trains inside the game. At GDC 2024, the team broke down the architecture. The rule from day one was simple: build a system, let fun emerge. To make that rule run, they removed every non-physics object from the game world. Gates, cogs, doors. Everything got rebuilt as a physics-driven object. Two layers of physics underneath: Havok (the same commercial engine powering Half-Life 2) at the bottom, Nintendo's in-house physics layer on top. Every wheel in TOTK is three rigid bodies: wheel, motor, shaft. Torque from the motor flows through the shaft. Friction with the ground creates forward motion. That's why a player-built train rolls correctly even though no developer ever scripted "trains." The cooking pot is the funniest piece of the architecture. Nintendo added a joint at the bottom so soup wouldn't spill on uneven terrain. Players figured out the joint was a ball-and-socket and turned it into vehicle suspension, robot arms, and laser turret mounts. None of that was on the design doc. Sound runs on the same trick. There is no pre-recorded "wagon noise." Every sound emerges from rolling wheels, jangling chains, and creaking joints colliding in real time. The director called it a physics engine for sound. The audio team said on record they don't recognize half the final sounds because the system made them. All of this runs on a Switch with 4GB of RAM and a 10-watt power budget. Studios with 10x the hardware budget can't let you put a barrel on a horse. Tears of the Kingdom lets you build a train.