How Dome Keeper focuses on systems that feed into one another

This interview is part of our Road to the IGF series. The IGF (Independent Games Festival) aims to encourage innovation in game development and to recognize independent game developers advancing the medium. Every year, Game Developer sits down with the finalists for the IGF ahead of GDC to explore the themes, design decisions, and tools behind each entry.

Nominated for Excellence in Audio, Dome Keeper tasks players balancing their time between mining for ore and defending their fragile planetary base from creatures that don't want them there.

Game Developer caught up with the game's director and several people who worked on its sound design to talk about creating a loop where several mechanics feed into one another (making them complex together but straightforward individually), their thought process on creating upgrades that make the player feel like they're getting stronger and more capable, and how they weave complex moods (and tell you a lot about what's to come) with the sound effects and audio.

Who are you, and what was your role in developing Dome Keeper?

Habermann: I'm René Habermann and originally made Dome Keeper with my wife Anne Hecker. She was doing the pixel art and I programmed, designed, and directed the game. We quickly got Cameron Paxton on board to create music to fit the calm and isolated mining. A bit later, Martin Kvale joined us as a Sound Designer, shaping the whole soundscape of dome.

What's your background in making games?

Habermann: I've been making games since my early teens, teaching myself programming with Blitz Basic. Eventually that lead to studying IT in university and working in IT due to a lack of educational options for gamedev in my region (Saxony in Germany). It's much better now, but back then there were no clear paths into gamedev.

I never stopped making games though, and eventually convinced my (then) girlfriend Anne to support this by making pixel art sprites. But we were stuck in the "start projects that are too large, lose motivation after a few months, repeat" loop that many gamedevs know. We started doing game jams in 2017, which finally was the key to us building the skills to actually finish something and learn how to make a proper game. We became full time gamedevs 2022 by getting published by Raw Fury. Before that, we were only working in our free time.

How did you come up with the concept for Dome Keeper?

Habermann: We made it during a game jam—Ludum Dare 48. The theme was "deeper and deeper," so one very obvious choice for that was mining. It was our tenth Ludum Dare, and this time we didn't want to be clever but just make something non-experimental which we knew we could make good and polish in the three available days.

I don't enjoy "single system" builds where you, for example, mine for mining's sake or survive so you can survive more. I wanted to have a real gameplay reason and motivation to actually go mining. This is where the monsters came in, resulting in the 2-phase gameplay. I initially thought of asteroids coming down and hitting the dome, but Anne made monsters in a mockup that were a very natural fit. So overall, for us it felt very straightforward with the game just naturally evolving.

It was interesting afterwards to see many people draw comparisons to a ton of different games, most of which I hadn't played before: Motherload, Steamworld Dig, Missile Command, Risk of Rain, Dig Dug. I think that was a lucky coincidence as people had a lot of nostalgic love for Motherload, especially. And it's a great sign if people can quickly understand your game and relate it positively to other games they like.

You can still go and play the game jam game, and I think it's interesting how true Dome Keeper is to that experience.

What development tools were used to build your game?

Habermann: The game is made in the Godot Engine, a fantastic free and open source engine. I especially like it for making 2D games. Other than that, we were using Aseprite for the pixel art, Logic Pro for sound work, and Ableton for music work.

Dome Keeper is split into two very distinct phases: mining and defending. What appealed to you about having these two styles?

Habermann: To me, it isn't even about the appeal of the phases by themselves. It was always about the interplay between the two phases—the battle giving a reason to go mining, but also being an immediate "show floor" for the fruits of your mining labor in addition to the mining upgrades you can get. What I also found crucial was the emotional/pacing balance you can get with this. You have the tense battle where you are fighting for survival. That is offset with the strangely calm mining phase: which is still under a time constraint which means you have to keep busy. This creates a core loop that works well for many people, often getting into a good flow of play. The appeal for me is always in interconnected systems motivating and influencing each other, building complexities in play but not in mechanics.

What thoughts went into designing how these phases would play, mechanically? How did you design them so they would fight for the player's attention and time, in a sense?

Habermann: Generally, one big goal was to make the game very easy to pick up. That's always important for game jams, and it turns out it doesn't hurt outside of them either. So, the mechanics are made as simple as possible with the complexity coming from the interactions and interdependencies.

One central part of both phases are the upgrades. You can spend your resources fundamentally on improving your mining or your battle capabilities. The upgrades should be a very strong representation of your mining success. Key to that for me is making all upgrades very powerful. It feels great to see big power jumps and it's also important just to feel the difference an upgrade makes.

On the battle [mode] specifically, the design is centered around the capabilities of your weapon, the unlocked upgrades, and how both play together with the set of monsters. As with anything in the game, I'm always trying to only add things that are meaningfully different than already-existing content. That means each monster should pose its own challenge in battle. This doesn't mean that it needs to do something different, but that the player needs to do something different depending on the monster they are fighting.

Mining, on the other hand, should be the main activity largely because the battle was never going to be complex enough to enjoy minutes-long instances of it. For mining, it was always clear that with the most simple mining mechanic possible, the complexity has come from elsewhere. What you can see in-game are hundreds of micro-decisions you take as a player that make this feel good: which direction to mine, which resources to focus on, how many resources to carry, etc. This gets interesting because of the time constraint put on the mining by the battles—otherwise you wouldn't really need to decide anything interesting. You make all these decisions optimizing your run into the mine to best utilize the time until the next wave of monsters approaches. So both modes are tied together like this, with mining needed to survive the battles, and the battles putting constraints on the mining.

What tools did you want to give the player to make either of these phases easier to navigate? How did you design the upgrades players could get?

Habermann: Upgrades are central here, but [so are the] gadgets. Gadgets are little helpers you can find underground which open up the gameplay to new possibilities. The goal here, again, was to have gadgets that can fundamentally alter the way you approach each phase. One of the best examples here is the lift, which enables you to stop carrying resources back to the dome yourself, and leave that constant part of gameplay behind at some point. For combat, it is more about a synergy with your main weapon and your chosen weapon upgrades as well as an adaptation to the set of monsters of the specific world you are on.

With the upgrades, it was the same as everything in the game: every upgrade should be meaningfully different. In addition, you should immediately feel the difference an upgrade makes. If we can, we also have upgrades visually and audibly change the game like the laser growing in size and sound with the power upgrades you can get. Upgrades are very interesting to design. On one hand, you want to give some options but also keep the mechanics as simple as they can be. There needs to be a balance between progression and mechanic changes, too. If the upgrades never change or add mechanics, it's a bit boring. If they do it too much it becomes laborious to understand and reason about.

Finally, with the upgrades all wanting to push the player forward in power, a big challenge is to balance the game so that it does keep being a challenge despite all those OP upgrades and gadgets.

How did you design audio and effects for two different play styles? What thoughts went into sounds that fit a world where players would randomly have to shift activities in ways that, to me, would seem very different, tonally and musically?

Paxton: During the playtest phase, we realized that music during the battle actually decreased the tension a bit, so we decided to lean heavily on sound design for the atmosphere of the battle phase. Each monster has its own ambience which attenuates based on the enemy number as well, so experienced players can read a lot from the ambience as they hurry back up to defend their dome. Now, the only time music plays during battle is the final wave after the relic is retrieved. This lets the player know that this battle is unique and that the end of the round is in sight.

Even during the mining phase, music can be relatively sparse, only playing every 2 or 3 cycles. This makes the music more of a treat for the player to hear, and occasionally adds a little more atmosphere to the gameplay.

Likewise, what goes into composing music that feels suited to exploring other worlds? What ideas went into capturing that sense of being on a strange, unknown world with the music of Dome Keeper?

Paxton: Fortunately, I had a chance to play Dome Keeper (then Dome Romantik) when it was still in its game jam build. The experience and game play loop was pretty much there from the start, so I had a pretty clear direction for the music.

I wanted to capture the same sort of loneliness and isolation that you feel when listening to a Metroid soundtrack, without directly referencing that series. I took a lot of cues from the music of Boards of Canada—beautiful synth sounds that are beginning to crumble and fall apart.

The original game jam version of the game had a more lo-res aesthetic, so the tracks also had a lot of bit-crushing to hint at older hardware, but we decided to make the music a bit brighter and full when the graphics were updated for the full release.

For the second keeper, The Assessor, we wanted to create a completely separate soundtrack and vibe to match the difference in gameplay style. I stuck with the same sort of somber and lonely atmosphere, but decided to use piano at the primary instrument. The Assessor, in many ways, feels more refined and skilled at their work than the Engineer (the first Keeper) does, so I wanted to create a vibe that matched that idea without veering too far away from the music that was made for the Engineer.

The game is filled with all manner of menacing alien creatures that aren't keen on your presence. How did you design their looks? How did you design them while keeping them feeling mysterious and unknowable?

Habermann: It is funny, their original look was, in large part, influenced by this being a game jam game. Anne chose an 8 color palette and a 320x270 resolution, which leaves very limited room to show details in addition to having a background world. The single-color monsters also meant they were very fast to animate, which is very important if you only have 3 days to make a game. That again all came naturally, and people enjoyed the mysterious look.

One influence that many people recognized was another game called Heart of Darkness. Anne saw it on a stream from one of her favorite people, and was inspired by that (also because it just naturally fit with the other constraints). We later experimented with giving the monsters some more details, but the feedback from players was very clear: the single color shapes are best for this. It seems true that the best things happen in your mind, so a key thing was to not visually "overshare" the nature of the monsters, leaving more room to player imagination.

The physicality of the monsters was centered around them being very wild or enraged, and some of them also being a bit goopy. So, the first monster smashes his body full force against the dome, laboriously pulling itself away from it afterwards in a seemingly self destructive act. That brutality was also important for us to contrast that with the cozy nature of having a beautiful dome you want to protect. Later, we also enjoyed surprising the player; for example, by having monsters that do some transformations.

Also, what ideas went into how they sound? How do you create an animal sound that feels like it's from another world?

Kvale: We needed to make the native creatures feel different from the player avatar, so I made them seem and sound strange and dissonant—unharmonious. I think the sound design of the Keepers, technology, and items have a lot of intimate and intricate elements, and the monsters are the opposite by being eerie and less detailed. They are created to raise the tension by emitting their shots, shrieks, dives, deaths. The more monsters [are] around, the more chaos and stress, rattling of your dome, as you are getting closer to death. So each sound doesn´t matter as much as how many, how often, and how far away from the surface you are.

Each monster also has an ambience that tells you a little bit about their behavior and how dangerous they are. When you are returning to the surface to defend against a new wave of monsters and you hear an ambience that you haven't heard before, you know there is something unknown on its way and that you may be in trouble.

We have some pals, like Drillbert and Drilliam, who came with you from your world, and they sound closer to your tech and exploration type of sounds: chirpy and quirky. They are handy little digging buds that hammer away at tiles with small “pfott pfott pfott” sounds and make cute little screams when you thrown them down towards where you want them to dig. Their sounds make them feel at home in the exploration and mining phase. They populate the underground areas and make them feel like there is activity happening there.

The audio effects loan a lot of weight and impact to mining, being attacked, and fighting back. How did you design effects that would make actions feel satisfying and attacks feel terrifying?

Kvale: Dome Keeper is a game with two distinct stages: an exploration part and a combat part. Each half needs to work on its own as well as balance against the other, so the sound design has to support this dynamic.

The sound design for exploration is intended to invoke curiosity. It's chirpy and built from a lot of intimate and small Foley parts found in my home. The sounds are layered so that each one shifts and changes every time it's played with some degree of randomization. We wanted the exploration to feel safe, so the sounds you hear help by being playful. Therefore, what you are hearing underground is the sounds of items, resources, the player avatar and its technology, with less of a focus on background atmosphere.

I think my favorite sound from exploration is when you recharge your sonar ability. It's such a strange little knotty sound—analogue and almost like some odd rubber wheel inside an old mill. It would have been typical to make a sci-fi high frequent splutter of a powerup charge sound. Instead, it is something from the real world, warm and intimate—it really makes me feel the technology of the keepers is something wonderfully weird alongside with the things you uncover down in the dirt.

We decided to add tones and melody in layers that peek out in the mix when the music isn't playing. This makes the exploration of the depths feel curious and gives an insight that the keepers are in harmony with themselves when they are exploring, not fighting.

We didn’t want these elements to clash with the music since we didn't want to add details and clutter to distract from Cameron’s eminent score. As long as the music plays, you only hear the functional layers in the sound design: the digging and the sound of hitting ore. But once the music dies out, the world that held its breath slowly starts filling in the blanks with harmony. Mining a water-vein gives small bell chimes, hearing an artifact chamber reflected in a sonar ping is a musical promise of an exciting powerup.

However, each harmonic voyage ends with a dissonant alarm beep. The alarm starts, and with it comes the ambience that is defined by the types of creatures attacking your dome. The atmosphere has shifted to being tense and atonal, densely packed and everything the soundscape below is not.

As you arrive back on the surface, the monsters will be there. Their sounds are aggressive, distorted, synthetic. They punctuate the tense ambience, and each hit reverberates through the dome’s glass structure. You get seated in your dome’s control center and through familiar chirps start up the process of defense. Your weapons and abilities may feel weak to begin with, but will grow in power as you upgrade them. At their strongest, they feel lethal and efficient. Quite the contrast to the exploration sound effects of the keeper. The weapons will quiet the cacophony of the monsters attacking until the very end, where the tension resolves in a calm bell chord. Then, as another wave is cleared, you are back to your quirky and strange mining. Rinse and repeat.