Welcome back to another Core Decay dev blog entry! This time we will be looking at how Core Decay approaches level design, looking at what motivates the way virtual spaces are designed and envisioned, and exploring a concrete example of this in how the design of a bank office has changed throughout the level design process.
On Visual Variety
However - before getting into all of that, I first want to recognize that most of what has been shown on this blog so far has been footage from the Brussels location, and this will continue to be the case for a while since it's the part of the game I happen to be working on at the moment. There's nothing wrong with that in itself, but I want to emphasize that the entire game is not dreary nightscapes! It's true that Deus Ex 1 did do exactly this and did it very well, but for Core Decay I wanted a larger amount of visual variety - a good comparison here would be Deus Ex: Mankind Divided or Dishonored 2, both of which incorporated a wide range of times of day and weather.

To illustrate this point, above is a small collage of a few (but not all!) other Core Decay locations across Africa, Antarctica, Asia, and North America. Do keep in mind these are in a far less polished state than Brussels, and will receive comprehensive work on fidelity and lighting, but nonetheless it should make for a good example!
Mundane Beauty
But for now, let's get back to Brussels - more specifically, a small administrative office of the Haupstadt Global Bank.

Wait, that doesn't sound like a particularly exciting location.
It absolutely isn't - and that is exactly the point. An easy trap to fall into, I believe, when thinking of these kind of immersive sims, is that they are all about the cool stuff. Secret agents! Huge skyscrapers! Underground bunkers! Secret research facilities!
These elements are important, and indeed Core Decay features plenty of all of these things - but they are not at the heart of what makes many of these immersive sims so captivating. It is not about the spy thriller - it is about the mundane. Harvey Smith said it best during a post-mortem of Invisible War:
"A lot of what made Deus Ex great was the familiarity, the groundedness. You're going through an alley, jumping up a dumpster to get to a fire escape to break into somebody's apartment. And we've all seen alleys and chainlink fences and dumpsters. That's why it's so powerful."
All of the larger-than-life parts are crucial as well, but they ought to be seen as building on top of a foundation of normalcy. Only by rooting the player into a world that feels believable can they feel like when the really cool things happen, they are genuinely exciting.
Obviously you can apply this mindset to games - or fiction - as a whole, in that it's often a good idea to establish a grounded frame of reference before leaping into the higher energy parts of a story - this is hardly a new idea, even the classic concept of a three act structure is built upon this. However, I have found that in games this is less commonly considered; it is as if there is concern that the player might lose interest if what they do feels too close to everyday life. In some genres this might absolutely be the case, but this is an immersive sim - it lives for these grounded experiences, and to truly captivate the player it ought to embrace this.
Designing Spaces In Core Decay
With this philosophy in mind, let's look at how Core Decay approaches level design. This approach rests on two pillars:
- Level design should follow real-world logic and levels should be thought of as real-world spaces rather than abstract gameplay spaces.
- The game's breadth of gameplay mechanics makes this engaging no matter what a location ends up designed like, since there are always enough mechanics to correspond to real-life obstacles.
In many games, it is common to design levels as vehicles for gameplay mechanics, then followed by what it actually represents being approached like set dressing. I want to stress that there's nothing wrong with this - but for this kind of game it is the entirely wrong approach to take.
Rather, we design levels as vehicles for logical cohesion and narrative. Gameplay mechanics are not considered in a vacuum, but rather naturally emerge from real life parallels. If bringing design closer to real life makes the game less fun, we first try to ask - how would you deal with this in real life? Could we keep the design and make that fun? A good example is the addition of multiple kinds of flashlights, as a way for the player to manage dark spaces.
We do still start out in the abstract, but it's less about gameplay and more about scope. More specifically, level design follows this general pattern:
Phase 0: Preproduction
- A vision for the location as a whole is laid out, with narrative context, visual storyboards and so on.
- The basic scope of the location is established, and the player's critical path is laid out - that is to say, a way for the player to physically get from point A to point B throughout the location. The specifics of this path will change significantly throughout the process, but some form of starting point is useful.
Phase 1: Blockout
- A simple blockout is made to correspond to critical narrative beats and the player's critical path.
- Fine details are unimportant here and most of this design stands to be altered significantly over time - but it is important to start with some sort of spatial reference for further work.
- Actual gameplay details - as in, what kind of obstacles are in the player's way? - are not prioritized at this stage.
Phase 2: First Detailing Pass
- The blockout is gradually replaced with higher detail assets and lighting/VFX work, to better convey the actual location and the big picture. It's important to do this early, since further level design work necessitates a sense of the overall mood and atmosphere. Note that this still stands to change a lot over time in terms of design - so far we're just building out the simplest possible spatial framework, in preparation for further level design work.
Phase 3: Evaluation
- At this point the current scope of the level can be evaluated. Does the physical size of the level feel appropriate? Should it be expanded to account for particular things? To give an example of this, in the case of Brussels, the initial iteration of the level featured only a very minimal amount of Brussels streets, with the greatest focus being on the Array skyscraper. After testing it felt like a good idea to turn this location into a full city hub, and so the scope of this particular level was expanded upon.
Phase 4: Second Detailing Pass
- By now, the level exists as a series of basic locations to take the player from beginning to end, and a sense of the scale being appropriate to convey all the narrative and immersive elements.
- From here, we can go from one area to another within the level, and start considering it as a real-world location.
- There still remains much work to be done even after this phase is completed - though we'll cover those parts another time.
And here is where we begin the proper part of this blog post!
The Haupstadt Global Bank

The HGB is the fiscal arm of the Hauptstadt Group, briefly touched upon in a previous blog entry. Long considered a respectable financial institution, and the only one operating in all major nations and city-states worldwide, it has become a cornerstone of society - but one resting on increasingly volatile foundations.
In Core Decay you come into contact with the HGB in a variety of places, though none more so than in Brussels. In fact, an HGB office is among the first things you may encounter as you explore the area around where you arrived.


This is a bank office, not a bank - which is to say, there is not much money to be found here - but as a way to obtain information and unique ways to access other parts of the city, it can be a very valuable target indeed.
Looking back at the process detailed above, let's look at how this office has changed lately as we've finished up the last phase of its design! We'll start at a point where we've begun - but not finished - the last step of detailing and worldbuilding work. At this point, this area of the level could be viewed as such:

The broad strokes of this area have been completed - we have a sense of roughly how large it makes sense for this building to be, and where within the city it is. However, the details of exactly how it connects to the rest of the level remains to be established.
Here we see the first important principle - we'll want to add more details here, let the office connect to more parts of the level and make it overall more interesting to explore - but we do not want to do this by thinking in terms of mechanics-first. The point is not to ensure the player always have a lot of choices - this happens anyway, and if sometimes choices are more limited, that only makes things feel more natural - but rather to now look at this office like a real location, add details based on that, and the gameplay will follow.
Had we instead gone for a mechanics-first approach, we run the risk of making the level design feel too artificial, as if there's a game designer who created this bank office and not a team of engineers. Of course, it is a game designer creating the office, but we want to keep the illusion as strong as possible. This world was not created for you - you are simply trying to survive in it.
Adding logical details
The way this is actually approached is actually a lot simpler than this - going building by building, area by area, and now asking some really interesting questions. Who would we imagine built this? Where in the world - does it need weatherization? Why was it built, and for what purpose? Does it account for everything employees would need - bathrooms, HVAC, recreation, fire escapes? Does it need protection? From who? Are there security systems, guards? And so on.
In asking these questions, that have to do with worldbuilding and narrative - not mechanics per se - we ensure that the spaces feel natural. And because so many of these elements inherently come with gameplay mechanics, even before we've done any additional gameplay tweaks (which do, of course, also have to happen over time) it starts feeling engaging and fleshed out.
But enough theory! Let's look at a few actual changes from the last couple weeks in service of all this!
Surrounding areas
Some changes to the general area were made to further a sense of worldbuilding (which secondarily ends up giving the player a few more ways into the bank office, should they pursue them). The nearby apartment building, previously entirely inaccessible:

Was fleshed out into an accessible corridor:

Leading to a new small back alley:

Note the windows towards the other side, which connect to the office:

These provide another way in - but more importantly, they provide a better sense of place (letting the player look out from inside the building and vice versa) and makes the bank lounge area feel more believable (after all, you would think the back part of the office would also have some windows!)
HVAC
Turning our focus back to the office itself, let's start out with the addition of a ventilation system. There were some hints of this already - note the AC units on the walls, and ventilation shafts on the building exterior - but the addition of a full HVAC system felt like a logical addition that would add a bit of believability.
To start, an exterior air shaft was added, turning this part of the exterior from this:

To this:

It already looks a bit more visually compelling! Even when not actively trying to reach the vent, it makes for a nice presence:

True to our design philosophy, the actual interior of the vent is unlit and requires the use of flashlights, night vision, or simply navigating in the dark. This is not always the case - but many of these kind of shafts are just as dark as you would imagine. By and large, we represent the world as it makes sense, and then give the player the tools to manage it.

As these shafts connect down towards the actual offices, you can see patrolling guards as well - a useful tactical advantage!

Within the office itself, there was already one vent connecting the meeting room and adjacent corridor:

This was useful to get a sense of the overall location up until this point, but makes a little bit less sense now. This was thus changed to a door leading to a maintenance closet, and in there is the vent leading to the corridor. Same general gameplay purpose, but feeling far more like a natural part of the building and less like something placed for the player's benefit.


Manager's Office
The office of Ben Hendersen, the (insufferable) manager, was also given a proper narrative pass to better reflect his personality - before:

And after:

There is an entire story to unravel here, and since none of the actual employees are around during the middle of the night, environmental storytelling becomes very important as a way to make these narratives feel more real and spaces more lived in.
Lounge
The lounge had a few windows added, as we already mentioned, looking out at the back alley. Before:

And after:

Result
There have been many, many more changes made, but these examples should illustrate the general thinking behind how levels are designed and considered. After these revisions, the overall layout of this area has gone from this:

To this:

On a surface level, this is similar to simply saying "We need to give the player some more options, let's make sure we add some vents and side areas" - but since that is a secondary effect of simply designing world-first, it ensures that when and where areas are added, they feel like a natural part of the city. This also lends the game a sense of asymmetry which works very well - sometimes you'll have lots of options and sometimes just a few, and you can tell just by context which is more likely to be the case.
Wrapping up
To conclude this post, I would like to give a big thanks to Johnny Josefsen, who has been doing a fantastic job helping out with level design these last number of months. Given recent circumstances, progress has been slow, so his efforts have been invaluable. Also a big thanks to all other level designers who have been on this project in the past - I appreciate all of your work enormously!
...well, this ended up being a bit longer than I had anticipated! I do hope that it's been an interesting peek into the internal design process - feel free to let me know what kind of focus for the dev blog you would like to see in the future!