The secrets to gaming gravity

“Find the fun.” Recreation improvement’s widespread chorus can manifest because the creation of a brand new recreation mechanic, the refinement or mixture of current mechanics, or making one thing easy — like leaping, flying, and preventing — really feel nice. Even falling.

In video games like Fortnite, Apex Legends, and The Legend of Zelda: Tears of the Kingdom, plummeting from the open skies to the exhausting floor beneath is an expertise. Simulated gravity pulls gamers downward, and recreation mechanics allow them to float, spin, and flourish as they fall. Simulated air friction might gradual their descent, whereas visible results like movement strains and field-of-view trickery assist convey a way of velocity. Rocketing again upward to the skies, whether or not by leap pads or just the power of a recreation character’s two legs, is outlined by a separate pressure that wants to really feel enjoyable, too.

Gravity is a part of the physics engine of each online game, says Chris Winder, main gameplay engineer at Apex Legends developer Respawn Leisure. “The gravity in Apex is about twice that of normal Earth gravity,” Winder mentioned in an e mail to Polygon. “This, combined with similarly increased jump velocities, is one trick games use that can help to make the game feel faster while still feeling within the bounds of realism.”

Physics simulation is usually regarded as a operate of simulation video games just like the Gran Turismo sequence or Kerbal House Program, however Winder factors out that “it’s present to some degree in nearly every game we play, from Super Mario Bros. to Rocket League to Apex Legends.”

Video video games can’t solely manipulate the power of gravity to meet their wants, they will merely ignore it when they need to — all in service of creating it really feel good, mentioned Jeremy Russo, recreation director at Velan Studios. His studio’s sports activities title Knockout Metropolis makes use of a gravity impact impressed by preventing video games to assist the sport really feel higher. (Apparently, Knockout Metropolis’s gravitational fixed takes a distinct strategy to Apex; it’s about half of Earth’s gravity.)

“Something we do both for gameplay reasons and for improved game-feel is briefly override normal gravity and character velocity for certain abilities,” Russo defined. In Knockout Metropolis, the developer makes your character hover briefly whereas throwing the ball mid-jump. “The gameplay reason for this is because the throw animation takes a few frames before the ball is released, so if we continued the player’s full velocity up or down then the ball was often thrown into geometry. It also just felt wrong, so we took a cue from some brawler and fighting games that briefly hover players in the air when they melee attack.”

Russo says “the extra level of polish to make this feel right involved resetting the player’s velocity if they were on their way down, or setting a new slower velocity if they were on their way up, because actually hovering at a specific height for multiple frames also felt wrong.” His group utilized this similar methodology, with various levels of special-case adjustment, to plenty of talents, like catching, dashing, and balling up.

Picture: Velan Studios

“Gravity is a force that pulls stuff ‘down’ every single frame of the game,” mentioned Chris Mercado, technical designer at Velan. “The fun comes from deciding where ‘down’ is! [We] can mess around with both magnitude and direction as much as we want. Some games work with a constant universal down (Super Mario 64), others have custom spherical gravity (Super Mario Galaxy); at the end of the day, gravity works the way the devs need to make the game they want to make.”

These forces transcend the anticipated up and down of leaping and falling, Winder mentioned. In Apex Legends, gamers can use leap pads and gravity lifts to push themselves upward (then fall). The similar physics-based strategy additionally applies to issues like grappling hooks.

“There’s a lot that goes into how these elements move players around to make each of them feel fun and useful,” Winder mentioned. “This can mean accurately simulating the real physics of a player launching through the air or being pulled by a grappling cable while also enabling some less-than-realistic inputs to this simulation to give players the control they expect.”

Apex’s Legend Pathfinder has a grappling hook that pulls the participant towards a grapple level, “but looking in a particular direction to the sides applies a small force so that players can ‘curl’ the grapple,” Winder defined.

Respawn equally fudges one other Legend’s capacity. “Horizon’s gravity lift applies an upward force to players but also allows for directional input to move around in the lift and exit it,” Winder mentioned. “There’s also a hidden force that sometimes acts to keep people in the lift so they don’t accidentally fall out.”

Picture: Respawn Leisure/Digital Arts

That form of air management is innately acquainted to gamers of many video games. In Tremendous Mario Bros. and Sonic the Hedgehog video games, you may exert a pressure on a personality who’s jumped to obtain higher management of their jumps.

“As a developer, some of the things I find incredibly interesting are things that are invisible to most players that make platforming significantly more usable,” mentioned Velan’s Jeremy Russo. “The most obvious one is air control… you can’t change your lateral direction mid-air after jumping in real life, but most games give you some amount of control.” Builders apply comparable tips for jumps, Russo mentioned, by letting gamers leap just a few frames after they’ve walked off a ledge.

“The amount of control the player has while they’re in the middle of a jump is one of the most fun aspects to mess with,” mentioned Doug Applewhite, a programmer and designer. “It’s a surprisingly difficult situation to feel good and ‘right’, and there’s lots of options you have to play with.”

“I think it’s important to realize that the jump is often a player’s first connection to the physics of a game world,” mentioned Hunter Bridges, recreation director at Penny’s Large Breakaway developer Night Star. “The jump intuitively tells the player a lot about how the game works, often within the first few seconds of gameplay.”

Picture: Night Star/Personal Division

Bridges defined his studio’s strategy to leaping in its 3D platformer, explaining that Night Star needed to be certain its titular character’s “jump happened with no startup delay.”

“Penny leaves the ground on the first frame the jump input is detected,” he mentioned. “Some other games may wish to have a few frames of startup delay to illustrate anticipation, or otherwise better match the jump animation.”

Bridges, who additionally labored on 2D platformer Sonic Mania, mentioned that crafting leaping in Penny’s Large Breakaway’s 3D area presents a really totally different problem from that of old-school side-scrolling Sonic the Hedgehog platforming.

“In 3D games, you are always wrestling with the fact that your 3D scene is projected onto a 2D screen,” Bridges mentioned. When a recreation’s 3D digital camera pitches or rotates, “it becomes difficult to perceive distance along the camera direction due to foreshortening.” That’s one thing 2D platformers don’t have to fear about.

Builders work round that foreshortening drawback, Bridges defined, by making enemies bigger, making gamers’ jumps increased, and being extra tolerant of close to misses in 3D video games by fudging collision detection and giving gamers restoration talents. (“This is where Penny’s Ledge Pull move came from,” Bridges mentioned.)

Picture: Mobius Digital/Annapurna Interactive by way of Polygon

One of the fascinating implementations of physics because it relates to leaping and gravity is how Mobius Digital’s area exploration recreation Outer Wilds handles the easy act of leaping. It has to contemplate extra than simply the participant’s motion, but additionally the physics of a small photo voltaic system.

“With video games, you [have] to keep the camera near the center of the world’s coordinate space, or […] everything starts kind of jittering,” defined Outer Wilds co-creator Alex Beachum in a 2020 documentary concerning the creation of the sport. “So we’ve got to maintain the participant close to the mathematical origin of the world. […] However as a result of [in] ours, the whole lot’s shifting relative to one another, what I ended up doing is: Each time we apply a pressure to the participant, we simply apply an reverse pressure to each physics object on the planet that’s at the moment simulating.

“So when you jump in Outer Wilds, technically every planet’s jumping out from under you, and you’re more or less not moving. It works,” Beachum mentioned, “and we haven’t changed it.”

Beachum’s resolution to fixing an advanced math drawback by simulating leaping in Outer Wilds was applied out of necessity, however it additionally serves the upper goal: discovering the enjoyable.

“[A] player’s intuition of how gravity should work is generally more important than reality,” Mercado mentioned. “That’s why most space-combat games have air friction and terminal velocities! At the end of the day, we’re making fun interactive media, so our physics should facilitate that fun.”