Hollow Knight Game Design Document

A diminutive, seemingly unremarkable champion answers the call to adventure, delving into the unknown, travelling further with each skill acquired, with each battle conquered.

Team Cherry has more than a little in common with Hollow Knight – a game that propelled its creators from obscurity, to moderate Kickstarter success, to glowing reviews, to the top of the Nintendo Switch charts in a whirlwind few years.

"I was spying on Hollow Knight's Discord to watch the community's real-time reactions, and when I saw someone type in, 'Reggie said the words Hollow Knight, I can't believe it!' I burst out laughing. It was a good feeling."

That's William Pellen, Hollow Knight's game designer, co-director of the studio, and half of Team Cherry's creative core. The Reggie he's referring to is, of course, Mr. Fils-Aime, president of Nintendo of America, who, at E3 2018, took valuable moments out of the company's presentation to help sell the dream of a tiny Adelaide-based indie developer.

"It was amazing! Kinda scary, too, because it was our launch day and we were all the way in Los Angeles, so far from our office," Pellen says. "But mainly it was amazing."

Ari Gibson, Hollow Knight's art supervisor, co-director, and the other half of Team Cherry's beating heart adds that seeing Hollow Knight on the Switch is still "surreal" for them. "The game is built upon our love of classic Nintendo games, so this is the peak of a 30-year cycle: growing up playing them, gaining enough skills to create our own homage to those games, and releasing it on the same platform that inspired us in the first place."

Needless to say, the cycle paid off. Hollow Knight's PC, Mac, and Linux release passed the 1 million units sold threshold the day before the Switch launch – a milestone that took 15 months to reach. That pace has accelerated of late. In just its first two weeks on Switch, Hollow Knight sold more than 250,000 copies, adding Team Cherry to the growing list of indie developers finding success on Nintendo's handheld; a marketplace not yet flooded like Steam or the App Store.

And it all began with a game jam. (Well, two game jams, to be precise...)

Ari Gibson (left) and William Pellen (right)

The Pale Knight Rises

Pellen and Gibson met 15 years ago through mutual friends, but didn't start working together until shortly before Hollow Knight's development, when they began entering game jams together. Countless indie teams have been forged in the feverish days of creativity a jam entails – Team Cherry is no different.

Hollow Knight's protagonist – a silent, nameless, genderless, beknighted insect – was conceived during Ludum Dare, one of the world's longest running jams. For the 27th iteration, held in August 2013, a nascent Team Cherry created a top-down survival title called Hungry Knight, in which the now-familiar hero kills bugs to stave off starvation.

In a rare quirk for an industry typically terrible at preserving its own history, Hungry Knight is still playable on Flash games site Newgrounds – where it carries a user rating of one out of five stars. To put it bluntly, it isn't very good. Aside from Gibson's striking art style, and the pale-faced, nail-wielding insectoid, there are few hints at the quality to come.

In classic indie fashion, the next formative game jam on the path to Hollow Knight was missed completely. "We were on the lookout for ideas to work on," says Pellen.

"Shortly after [Ludum Dare] there was another jam with the theme 'Beneath the Surface,' which we thought was really evocative. We missed the deadline for the jam, but we kept talking about what sort of game we could make that would fit. We thought of the little insect knight exploring a deep, old kingdom beneath the surface of the world, and everything kinda snowballed from there."

If Hollow Knight had a single defining light-bulb moment, this was it. Metroidvania maps resemble ant nests anyway, so setting a game in a subterranean hive is an inspired idea: Hollow Knight is a near-perfect match of form and theme.

With a concept both Gibson and Pellen were enthusiastic about, development began. Being well versed in NES-era platformers, the pair recognized that nailing satisfying moment-to-moment mechanics was crucial. And in any platformer, that begins with the jump. "We wanted players to feel totally in control of their character at all times, so our model for movement was the Megaman and Megaman X series," says Pellen.

"The Knight has no acceleration or deceleration on horizontal movement. The jump has a lot of initial lift, releasing the button cuts vertical speed quickly, and the dash completely arrests vertical movement, shooting you forward instantly."

This all adds up to an unusually high degree of control in mid-air. The intention, Pellen explains, is to make players feel that "any hit they take or mistake they make could have been avoided right up until the last second. It's a principle we tried to roll out through the rest of the game – but it all started with the Knight's run and jump, the very first things to be coded."

Hollow Knight's jump feel was based heavily on the Megaman series

Descending Into Hallownest

The Knight now needed a compelling world to venture into. The secret to any great Metroidvania is how well its map interconnects and loops back on itself, opening up previously inaccessible areas as abilities are obtained, giving players a true sense of discovery – all while subtly planting narrative seeds throughout.

Hallownest, a once-thriving kingdom fallen into decay, excels at this. As players delve deeper, the grandeur of the old world seeps through the rot. The City of Tears, built underneath a subterranean lake, is blanketed by a perpetual rain that trickles down opulent, ceiling-high windows hinting at glory long faded; The Queen's Gardens, once the private sanctuary of an ageless monarch, are now overgrown with thorns and swarming with worse.

Gibson's hand-drawn sketches were scanned directly into the game engine, helping to create the vivid sense of place. "I photographed them with my phone and cleaned them up on the computer. From there it's just adding pieces into the world until it feels full," he told Game Informer last year. "'Keep it simple' was our visual goal. That mantra carried through to the rest of the art, and was probably integral in us being able to create so large a world in two years."

And a large world it is. During the opening hours, players can become hopelessly disorientated. This is deliberate: you can't feel like an explorer if you always know where you're going, after all. "We didn't worry too much," says Gibson. "It's a game based largely on Metroid, so the whole experience is about the joy of getting lost and finding your way.

"Some signs are placed in areas that provide appropriate context, and we do lightly use the abilities you collect to keep players in safe areas... but we didn't stress. Instead of focusing on ways to direct players, we focused on giving them interesting things to stumble on as they found their way through the world: hidden characters, treasures, and battles."

Team Cherry says maintaining that sense of discovery while still giving players a useful map of the world was the single biggest design challenge faced during development.

"The map and the mapping system took a long while to come together," admits Gibson. "We wanted players to feel like an explorer entering uncharted lands, so we knew that the map couldn't work in a Metroid-style way. It couldn't know the shape of the landscape before the player did, but it also couldn't be so unfriendly that a player would turn off the game in frustration."

And there's a fine line between compelling and frustrating.

"Mechanically that meant purchasing simple maps from a cartographer and expanding on those yourself as you explore," Gibson explains. "Artistically it meant finding a visual balance for the map that suggested just enough, but wasn't a giant mess of overwhelming detail. Turns out drawing maps is tough! We threw out a lot of them before we reached the final version. In retrospect, we're pleased with how the system turned out. It's a wonderful balance."

This is the second digitally drawn map of Hallownest from development, showing item placement. Note the inclusion of the Boneforest near the bottom, an area that was cut from the game (more on that later)

In another inspired touch, the world of Hallownest evolves ever so slightly. By design, Metroidvanias always require a certain amount of backtracking. The trouble with this trope is that earlier areas become far too easy – tedious even – once the character has powered-up enough to face later areas.

Hollow Knight solves this problem by altering its starting area in the late-game: "The Forgotten Crossroads" becomes "The Infected Crossroads," now filled with a corrupting orange goo that blocks off well-travelled routes and mutates enemies into deadlier, more-level appropriate variations of their earlier incarnations.

"One of the most interesting parts of a Metroidvania is when you return to an area with a new suite of moves and suddenly traversing the area feels different," Pellen says.

"What was once a maze of one-way paths and dead-ends is suddenly open and free, and the enemies that were dangerous hazards before are no longer so deadly. In a way, the area 'transforms.' We had the idea to make this transformation literal by completely changing a starting area as you progress through.

"It makes for a nice surprise and gives you the sense the world is more dynamic and alive than you realized. We were relatively restrained with the idea, only majorly changing one area, but you could definitely extend this in all sorts of interesting ways!"

Crowdsourcing Inspiration

With five sections of the world completed, the team took to Kickstarter in November 2014, seeking the modest sum of AU$35,000. They passed their goal, bringing in AU$57,138 from 2158 backers. With the extra money, Team Cherry was able to expand the scope of the game and hire some extra help: David Kazi as technical director ("since he knew how to code," says Pellen) and Chris Larkin as composer and sound designer.

For an untested, unpublished team, the success of the Kickstarter didn't just provide funding: it let Gibson and Pellen know they were doing something right, a confidence boost you can't put a figure on.

"It was the first signal that, conceptually at least, that we were on to something cool," says Gibson. "We ran a beta several months after that, which included the entire first area of the game, The Forgotten Crossroads. It was the stellar response to that area that really cemented our direction for Hollow Knight."

With a now-invested community, Team Cherry began updating backers on progress at regular intervals. Strangely enough, this openness became the source of one of Hollow Knight's more unique ideas.

"During the Kickstarter we were asked in an interview what would happen to the player, mechanically, when they died in the game," says Pellen. "We said something like, 'Oh, it'll be a great surprise!' and then after the interview we realized we hadn't actually considered that yet..."

In numerous games players drop accrued currency upon death, which can then be collected from your corpse on the next run. Hollow Knight adds a unique twist to this, making players fight a ghostly incarnation of the dead Knight before regaining their cash. If it kills you, bad luck.

"We'd already completed the Knight's death animation, which ends with his head falling to the ground and cracking," Pellen explains. "We thought it might be interesting if you had to travel back to the place you died, find the skull, and crack it open to regain your money.

"Then we kicked around some ideas about the skull being possessed by an enemy, or suddenly fighting back, which seemed really funny. This evolved into the idea of leaving behind a ghost of your previous life that attacks you, which eventually became the 'shade' that you encounter in the final game.

"This is a really good example of a simple mechanical idea we made early on, that seemed inconsequential at the time, ending up having a huge impact on the lore and the history and the nature of the character you play as. Which happened a lot."

The Final Cut

Hollow Knight was slated for a June 2015 release, but with growing ambition and numerous Kickstarter stretch goals met, 2015 flew by. As did 2016. Cuts needed to be made.

"We removed one large area from the game, the Boneforest," says Gibson. "It was a huge later-game area filled with lava. Cutting it was tough at the time. It seemed so cool! But it was totally the right thing to do. William and I were already slammed with all the other enormous areas to build, and they all would have suffered for Boneforest's inclusion.

"We also significantly reduced the size of Deepnest, which seems unbelievable, given how huge it ended up being, but most players would thank us for that decision. Too long in Deepnest isn't good for anyone!"

The gaming landscape had also shifted dramatically by this point. In late 2014 when the Kickstarter ran, this console generation was relatively fresh; anything could have happened. But by early 2017, the promised Wii U version – a console on death row with a successor announced – was a millstone around the neck.

The tough decision to cancel the Wii U version and shift focus to the Switch was made. "We had done a fair bit of preliminary testing and it was running [on Wii U] with most of the basic features, but performance would still have required further work," Pellen says.

"It was hard because we loved the Wii U and we'd promised to get the game on there. But looking at the time frame, the Switch was fast becoming the main Nintendo console and our backers were already moving over. When we made the change, backers were excited for the shift and Nintendo was tremendously supportive through the process."

The Conquering Hero

There's no guaranteed path to indie success. Hits come from unlikely places and anticipated games flop all the time. But Team Cherry's open communication and compelling twist on a popular genre – a genre largely abandoned by its forefathers – gave the studio every chance.

In early 2017, from a "cozy" office nestled in the heart of Adelaide, Australia, Hollow Knight sprang forth. Not only was it an unexpected commercial hit, critics loved it. The PC release has a Metacritic score of 87; the recent Switch version sits on 90.

With a second playable character, Hornet, still on the way, and physical boxed copies of the Switch, PS4 and Xbox One versions due in 2019, the journey isn't yet over. It's hard to deny Hollow Knight's place as one of the most significant video games ever developed in Australia.

Back when Hollow Knight was just a loosely defined idea conjured from game jams, Team Cherry hadn't envisioned anything like this. "Our goal was always to get ourselves into a position where we could just keep making stuff, and we're grateful we've gotten there thanks to everyone's support," says Pellen.

"Defining success [back then] was easy," adds Gibson. "It was just, 'Selling enough to be able to make another game.' Had we achieved only that, we would have been happy."