The Making of: Hollow Knight Boss Keys (Patreon)

Hello! 

This Hollow Knight video was a huge endeavour, but I couldn’t be much more pleased with the result. I’m really happy with how I summed up the game, and the feedback has been great. 

This is my longest video to date at 40 minutes, but it’s made with the same density of information and detail in presentation as my normal 7-15 minute episodes. And I somehow edited the whole thing in little over a week. 

In this article I want to share some behind the scenes stuff on my process, and give you the complete interview with the game’s developers, Team Cherry. 

Researching the Game

Normally, the first thing I do with Boss Keys is to play the game through fresh. It’s either been too long since I last played the game, or I’ve not played the game before (in the case of Metroid Prime 3), so I need to just play through the title to figure out what I thought about it.

What was my experience, what did I like, what annoyed me, where did I get stuck?

Luckily, Hollow Knight is recent enough that I remember my first experience with the game well and didn’t need a second playthrough to gather my thoughts. I also had loads of footage captured from that 2017 playthrough, which helped with the final video and also showed where I went and what I did during my original experience. Very useful. 

So the next thing I did was to map out the game. To do this, I take a map of Hallownest, and make notes to show where I can go at each point in the game. 

For example, here’s my map for the explorable space following the Crystal Heart

This is a really important way of helping me understand the game’s structure. I can see exactly how the game expands as you pick up power ups, and look at the number of things you can do at each juncture. This was critical for the video, where I discussed how the game opens up after receiving the Mantis Claw. 

To do this, I have a map of the game on my Mac, in Photoshop. And then next to me, I have the game itself running on my PC. I use cheats (invincibility) so I can explore the game without worrying about dying. 

I also reached out to Team Cherry to ask them some questions about the game. It was nice to get some real developer insight into the production of one of these Metroidvanias. The full interview can be found below. 

Capturing footage

I had a bunch of footage in my archive from my 2017 playthrough, but it was missing a bunch of important scenes, such as the stuff with Zote, both and the bad and good endings, waking up Herron and Lurien, and various other bits I needed for the video. 

Whipping around Deepnest with noclip mode on

To get these, I installed a debug mod into the game which let me zoom all over the game really quickly and easily. I could zip to Deepnest to get footage of Herrah’s lair, then whisk off to the Resting Grounds to grab a video clip of Seer. 

But I also discovered that this debug mode could be used to make pretty pictures of the game. I can hide the play character, the UI, and the vignette frame around the game. I could zoom out, zoom in, and slow down time. I used this to make the area title cards and the Blue Lake to City of Tears transition. 

Oh, and this shot. That’s actually about seven different video clips from debug mode, carefully stitched together in Premiere. It took way too long to make, but I wanted to do something quite special and reveal the ant’s next design of Hallownest. 

Making the Motion Graphics

The main thing I needed to accomplish with this video was drawing arrows on maps. I do it over and over in the video, showing the route to the City or the multiple ways to Deepnest. 

Thankfully, there’s a handy new option in Adobe After Effects to attach a null object to a shape, allowing me to add arrow heads to a line and create these cute animations. 

I made icons for the Hollow Knight chart. Each one has a unique background, like the room where you fight Hornet or the Mantis Village for the Mantis Claw. 

I made the entire chart in Photoshop, exported it as unique images, and then put it together in Premiere, which allowed me to modify and move the elements when talking about how the sequence of the game can be changed. 

I also made these cute boss icons for the list of bosses.

A map of the infected crossroads with animated Xs over the blocked paths.

Animated area maps with stag pins. 

An animated node map of the game’s world (After Effects, using a technique I picked up while making the Pac-Man episode!)

Key words and developer quoted with animated flourishes.

Animated cards to talk about optional and critical locks. 

And more. 

Production

The research process had been going on all month, but I suddenly decided that I could make this video in time for Halloween if I got a wriggle on. This was on Monday, October 21st. 10 days to go. 

I wrote the script on Monday, rewrote it on Tuesday, and finished it up on Wednesday. I was out at the hospital on Thursday, but recorded the vocals and captured some extra footage on Friday. 

I normally don’t work weekends, but I took a few hours over Saturday and Sunday to process and edit my raw vocals into a usable audio track. 

On Monday, I made almost all of the motion graphics. On Tuesday and Wednesday, I put in all of the game footage. And on Thursday, I did the music and finishing touches. 

I’ve never worked so hard and it was exhausting, but also kind of fun to have a deadline to work towards. There was a real “am I going to make it?!” tension over the week. 

But I did make it - just! - and got the video out in time. Which actually was quite a bad idea because it got buried under all the other Halloween specials, and people were too busy trick-or-treating to actually watch 40 dense minutes of video game analysis. Whoops. Oh well, you live and learn.

Traffic has picked up since then, and it's now cleared 200,000 views. 

In conclusion 

I really enjoyed making this video. I learned a lot about Hollow Knight, picked up some new editing techniques, and I think I did the game justice. I hope you liked it, and will permit me a bit of a rest for a couple days!

Anyway, here’s the full interview:

Mark: What were your first steps when planning out the world design of Hollow Knight?

Ari Gibson and William Pellen (Team Cherry): Hollow Knight spawned from a game jam (Ludum Dare 2xx) with the theme 'Beneath the Surface.' Before it ever grew to its final, grander scale, the jam version established Dirtmouth, the hub town, and the fossilised caves below, which later became the Forgotten Crossroads.

In a significant sense the Forgotten Crossroads and Dirtmouth are the purest expression of 'Hollow Knight,' a quiet maze of lamp-lit roads all cast in cool blue. At the time the intent was for the rooms to shift their placement based on repeat playthroughs, in a similar way to the recent (excellent) metroidvania Chasm.

As the Hollow Knight idea expanded beyond its game jam routes (we missed the deadline for submission!) we moved to a more singular structure partially for ease of development but mainly because we wanted to have more visible history and relationships between the spaces.

Mark: HK is very open and non-linear in its design. For example: after getting the Crystal Heart, you can access both the Monarch Wings and Isma's Tear. Why did you choose to make the game like this, instead of giving the player a specific order to do things in?

Cherry: The heart of Hollow Knight was always intended to be the exploration of a strange, ruined world, one that felt like a real place. Key to that was the player being able to forge their own way through it. We started with a basic, linear progression of item acquirement with the idea that we would allow that progression to break apart, branch out and wind around itself as the world grew. We wanted players to feel like their journey through the kingdom was their own, and part of that was removing barriers or opening paths to allow acquiring items or powers 'out of order'.

Mark: Many areas in Hollow Knight have multiple entrances (For example, after getting Mothwing Cloak, you can get to Mantis Village through both Queen's Station and Forgotten Crossroads). Was this an intentional decision, and if so, why did you make it?

Cherry: It was always intentional to give players different ways to travel to and through (and sometimes around) areas. It's part of that same idea, of giving players a world to explore, of allowing them to venture out, get lost, and find their way again. Some of these 'optional' paths were present in the planning stages (such as the two paths into Fungal Wastes you mentioned), and some of them we added when the opportunity presented itself. For instance, when Deepnest grew tall enough that the top of it was brushing against the bottom of the Queen's Gardens, we added a connection between them. If we can add a connection between adjacent areas, and it makes sense in the world, and it doesn't cause players to get stuck somewhere, then we do it.

Mark: Many of the bosses in Hollow Knight are completely optional in terms of reaching the end, or even the true ending. Why did you choose not to force players to see all the content you made?

Cherry: With Hollow Knight, we strive to make a world that feels vast and believable, one that exists beyond a directed path, or even a single playthrough. Hollow Knight's content isn't intended as a check-list to be marked off (though a small percentage will attempt that task!). Much of it exists to convey a sense that there's always something else waiting in the unexplored recesses of the world - fearsome enemies, strange characters, new areas, powerful items etc.

As designers we create a lot of stuff that gets hidden away, without worrying too much about whether everyone will find it or not. Just having it there, out of sight from most players makes the world more truly alive, and creates a very special experience for those few that do make the discovery.

Mark: It is possible to nail jump off of enemies, to reach some of the high areas that would normally require the Monarch Wings. Was this intentional on your behalf - and did you ever worry about the player breaking the sequence of the upgrades, and potentially breaking the game or getting stuck?

Cherry: We knew players would be able to sequence break using the nail bounce technique, and we absolutely wanted them to be able to do so. Watching players discover new routes is a huge joy for us and is a really empowering moment for a player.

Knowing this from the outset meant the world was built to accommodate unexpected behaviour. We even placed certain enemies and objects to allow some shortcuts, though the Hollow Knight community has uncovered many more skips that we'd never considered ourselves.

Notably, despite our best efforts, the PC release version included a spot at the bottom of the Kingdom's Edge area where a small number of players could find themselves briefly stuck if they hadn't yet acquired the Monarch Wings. This was patched out in the first week or so, but it does show that, for all our best efforts, allowing open exploration is a challenge.

Mark: How did the world layout of Hollow Knight change as development went on?

Cherry: While the world shifted and grew in a thousand subtle ways, most of the planned foundation structure remained consistent throughout development. In our early sketches, the Crossroads area branched left to Greenpath and the Fungal Wastes, the City of Tears rested below and the mine area (Crystal Peak) waited to the right. Areas were planned with revisits in mind, and those revisited sections eventually gained enough unique character to become their own distinct zones eg Crystal Peak, originally a small additional section of the Forgotten Crossroads, is now a major area, likewise the further Fungus area became the Queen's Gardens.

Of the few major changes one was the removal of an area called the Boneforest, a series of lava filled caverns, which we cut for both schedule and thematic reasons. Beyond that, there was some significant shifting of the City of Tears area, which repositioned the Soul Sanctum and saw several other towers cut. A subtler development was the Kingdom's Edge area, which wasn't originally planned, and emerged out of a need to house several ideas that hadn't yet found a home - the Colosseum of Fools, the Hive and a second encounter with the boss Hornet.

Mark: What experience were you hoping that players would have, in terms of exploring the world of Hollow Knight?

Cherry: We're hoping players initially feel lost, deep in the dark, alone in a dangerous world, one without barriers and with little safety. Over time, that feeling may shift to understanding and empowerment as players become more comfortable in the space and more confident traversing it.

Much of our approach is about removing or obscuring the sense of a developer's guiding hand. Instead we try to let the player loose in a wild world, not push them explicitly one way, and reward them for choosing their own path.

That approach is based on mutual trust and respect between us and the player. We know these are smart, dedicated people and we're confident that, through observation, tenacity and skill, they'll deal with the challenges the world presents and ultimately gain mastery over it. It's that mastery, in exploration, in combat and in understanding the story of the world that we hope creates a memorable experience.

Mark: What considerations did you give to helping the player know where to go, such as the layout of the world, or NPC dialogue?

Cherry: The obvious level of this is the many signposts dotted throughout the kingdom, and npcs will occasionally suggest directions to head. Importantly those NPC dialogues are mostly framed as 'there's an interesting place if you head this way,' not as anything too directed or 'gamey', so players are free to ignore those hints if they choose.

Ultimately, Hollow Knight (and to some extent its sequel Silksong), is a game about getting lost and slowly learning your way. It's a simple thing to provide more direction, just put in more signposts! But it'd be to the detriment of many players who, through initially being lost, find their own ways and begin to learn the layout of the kingdom on a much more personal level.

Mark: What considerations did you give to having a consistent difficulty curve throughout the game?

Cherry: Other than a very general idea of 'the challenges at the end should be harder than at the start' a smooth difficulty ramp was never too much of a concern, and that's okay! If anything we want to achieve an uneven feel, to vary the level of challenge all about the game's world. Coming up against a really powerful boss, or gliding through a series of simpler challenges with ease makes the world feel more real, less constructed. If the difficulty was too consistent in its growth, the world would risk feeling artificial.

If players did ever encountered a major roadblock in their adventure, our main concern was to always provide other options: Another path to explore, a power-up to make the challenge easier or a way to skip the encounter entirely.

Mark: What games, particularly Metroidvanias, were you inspired by? And did you break down or map out any games for research, as part of your development process?

Cherry: The three titles we often mention as the basis for Hollow Knight are Faxanadu, Zelda 2 and Megaman X. Our influence from those titles was our memories of them, the feel of the adventure, not any explicit single thing. In fact, we try to never look too closely at their maps or level layouts, or any other element of those games. Doing so may lead to unintentional or obvious reference, which we really want to avoid.

Mark: What did you learn about world design from Hollow Knight, that you'll be putting into Silksong?

Cherry: The most important note for us is: Work creatively, not clinically. Start with a simple plan and let the world grow and develop as we dive in there. That approach makes it feel natural, and the spontaneity provides an energy to everything that benefits the player's experience.

As developers, the world design we undertake is more akin to being the first explorers of a new land, trekking down hallways and into dark chambers to see what's there for ourselves, with only a rough idea of what we'll find. As it comes together, the world starts to dictate its nature to us. Water draining from above - there must be a lake up there somewhere. A ruined tramway - what caused it to be abandoned? Once those questions arise, we're eager to search for their answers, so the world expands as we journey further, creating new spaces, new creatures and new challenges along the way.

If, when that process is finished, we've uncovered a world that excites us, then it has a good chance of exciting players. That's the same approach we've taken for Silksong's kingdom, Pharloom, and we're hugely looking forward to delivering it to players so they can begin their own adventures there.