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How to build a basic 3D version of the level with massing, metrics, wayfinding, and playtesting.

Why build a blockout?

A blockout (also blockmesh or graybox) is a 3D rough draft level built with simple 3D shapes, but without any details or polished art assets.
The goal is to prototype, test, and adjust the foundational shapes of the level.
In the image below, notice the differences between the blockout version and the final shipped version. A shape might start as a gray block -- then after months of playtesting and art passing, the block becomes a stack of barrels... or maybe gets deleted entirely.
comparison of blockout vs final art-pass for "Docks" in Call of Duty: Modern Warfare (2019) by Brian Baker
Blockouts support experimentation.
It is "cheap" to delete or rebuild some rough blockout geometry, but throwing away finalized art passed work is "expensive" and wasteful.
When you are not confident about the level structure, it is best to keep it "cheap" until it is ready to become "expensive."
You can't playtest a design document or a layout sketch, but you can playtest a blockout and evaluate its flow, balance, encounter design, and metrics. This is the design phase when you finally start to discover whether the ideas will work or not. The blockout is just the beginning.
"... If we consider that [Neon White] shipped with over 100 levels, the team made “double” that amount in scrapped levels, and [the level] Smackdown alone had more than 50 changes made to it, we’re faced with thousands of tweaks and redesigns throughout the entire game. [...] Three years later, Smackdown is complete."
-- from How A Neon White Level Is Made by Blake Hester, Game Informer #350
early blockout of "Smackdown" in Neon White (2022) by Ben Esposito, Russell Honor, and Carter Piccollo (via Game Informer)

Key concepts

When blocking out, consider these aspects:
  • Massing is the general sense of volume and weight conveyed by the shapes.
    • Is this structure thick / heavy, or thin / light? What kind of place is this?
    • Landscapes need special consideration.
    • Composition is currently over-emphasized in level design culture today.
  • Metrics are the general scale, dimensions, and proportions of the level.
  • Wayfinding is the player's navigation process for learning the map structure.
    • How to help the player find the critical path / level exit? Does the player feel too lost?
  • Playtesting is when you run an experiment to see if the level meets its design goals.
    • Can most players complete the level? Do the encounters work? Is it balanced?
    • Playtesting is really important. This is the whole point of making a blockout.
example blockout video - "Uncharted: The Lost Legacy - Train Level Early Prototype" by Matthew Gallant

Construction methods

There are five common 3D level construction methods in games:
  • Primitives: arrange simple basic shapes like cubes and boxes.
  • Brushes / modeling: construct 3D shapes in the level editor.
  • Modular kit: connect pre-made pieces together, like Lego.
  • Sculpting: "paint" organic 3D shapes, useful for landscapes.
  • Splines: create math curves that procedurally generate geometry


Primitives are simple 3D shapes, like the default gray cubes and boxes built into a game editor.
Move / rotate / scale the shapes. Arrange them together, stack them on top of each other, make more complex groups of shapes.
This is a surprisingly powerful blockout method. You can always use this method in any 3D engine or tool, but you'll hit limitations with blocking out anything beyond simple boxy buildings.
Advice for blocking out with primitives...
Pay attention to metrics, establishing scale is tricky.
To make a ramp: make a long wide thin cube, then rotate to slope downward. To make stairs: avoid suffering and just make a ramp instead
To make a doorway: leave a gap between two walls, no door frame. To make a window: make doorway-like gap, then fill in with a short waist-height wall
dimensional massing diagram by Francis Ching, from "Architecture: Form, Space, and Order"

Brushes / modeling

Brushes are simple low polygon 3D shapes modeled in the level editor.
This was the main level construction method across the industry from 1990s-2000s.
We strongly recommend this method because it offers the most control and handmade feel, but unfortunately most modern game engines often have poor brush modeling tools. It can be tricky to figure out a workflow here.
Advice for blocking out with brushes / low poly...
Use a brush-based 3D tool that emphasizes low poly geometry.
Use a big coarse grid size based on metrics, the player's width.
  • Doom or Quake: 32u wide player = set grid to 32 or 64
  • Unity: 1m wide player = set grid to 1 or 2
  • Unreal: 60uu wide player = set grid to 50 or 100, or maybe 64 or 128
simple 3D modeling with "brushes" in TrenchBroom; GIF demonstration by Benoit "Bal" Stordeur

Modular kit

Snap together pre-made pieces of architecture from a kit of modular parts.
However, if the kit is badly designed or poorly configured, it'll be hard to use. If you're a beginner, you probably shouldn't try to make your own kit -- just download one instead.
For more on planning, measuring, and constructing modular kits, see Modular kit design.
For links to download free modular prototyping kits, see Resources.
Advice for blocking out with modular kit...
Configure the Grid and turn on Grid Snapping (how-to: Unity, Unreal)
  • use a large coarse grid based on module size
  • e.g. if wall modules are 5m wide, then set grid to 5
Use vertex snapping to align modules precisely (how-to: Unity, Unreal)
Just download a pre-made kit.
"graybox" blockout modular kit used for prototyping levels in Skyrim, image by Joel Burgess


Most modern engines have a sculpting tool that lets you paint and deform a flat plane.
We use this only for making big smooth shapes like terrain and landscapes; it's bad for hard surfaces like buildings.
But if landscapes are central to a project, there's no way to avoid sculpting.
For more on sculpting and designing terrain, see Landscape.
Advice for blocking out with a sculpt...
Sculpting is often a distraction for beginners. Making a mountain with a single click is so fun and empowering that you'll forget to do any level design. Be careful! Don't let sculpting tools seduce you!
Use a large brush size and focus on big core shapes first.
Define ground planes with the Set Height (Unity) or Flatten Target (Unreal) brush
Sculpt slopes as stepped terraces to define the gradient, then smooth it.
Avoid erosion / auto-generator tools, you need control over the design.
sculpting landscapes for the "Nagrand" region in World of Warcraft: Legion


Splines are invisible curves that generate geometry along the path.
These curves are also non-destructive; you can adjust a spline at any point and regenerate its geometry.
A spline is ideal for blocking out curvy linear forms like roads or rivers, where it can also automatically deform the surrounding landscape.
It's also possible to generate non-linear areas and buildings with splines too, but this type of workflow isn't common and usually requires custom tooling.
Advice for blocking out with splines...
Like sculpting, splines are often a distraction for beginners. Playing with splines is so fun that you'll forget to do any level design. Don't let splines seduce you!
Spline tooling varies. They became common only in the mid 2010s. Unreal has excellent built-in support for Blueprint Splines. Unity users are less lucky and have to try various plugins like SplineMesh or code your own splines.
Splines aren't magic. If you want to make anything more complicated than roads, rivers, or bridges, it will usually require custom tooling and a lot of art support.
animated GIF of a procedurally generated bridge defined with a spline in Unreal Engine 4; by Peter Severud (via Artstation)
Why not use a 3D art tool like Blender, Maya, Max, or SketchUp to blockout?
People debate this. Here's our take: 3D art tools don't let you tune gameplay, collision, encounters, or items. Playtests become slower and less frequent.
Example: on an unnamed AAA game, moving a rock requires a multi-step hour-long process: (1) load debug build, (2) find which file has the object, (3) open Maya, (4) edit file, (5) recompile game, (6) load debug build again to confirm change.

How to blockout

Here's a general process. If you're a beginner, or you're at the start of a new project, try to do everything. You will gradually personalize your own process and style.
  1. 1.
    Sketch layout
  2. 2.
    Add ground plane, scale figures, walls
  3. 3.
  4. 4.
    Diverge, iterate, and playtest again
  5. 5.
    Repeat step 4 until done

1. Sketch layout

It can be difficult to blockout without any plan, especially for beginners. Even a simple scribble can help a lot.
Look at the layout sketches below. The left sketch emphasizes the scale of each space, the middle sketch focuses on the relationships between the areas, while the right sketch is a more detailed floor plan drawing. Any of these sketches can work, any of them can help you plan a blockout.
Just draw something!
example: three similar but different layout drawing styles that can maybe help you plan the blockout... any of these are fine to get you started, JUST DRAW SOMETHING

2. Add ground plane, scale figures, and walls

Create a ground plane (or a big flat cube) near the center of the 3D space (0, 0, 0).
Use a light-colored gridded prototyping texture so that you can visually estimate sizes and scales. This floor object will help "ground" the rest of the level geometry, providing a horizon line and context for everything else to rest upon.
Add a player-humanoid scale figure to help establish scale.
If you don't have any humanoid assets, create a roughly human-shaped block to serve as a placeholder. The scale figure helps establish consistency and clearance for the player.
For more on common hallway / wall sizes and humanoid dimensions, see Metrics.
For links to free prototyping and blockout textures, see Resources.
example: a gray ground plane with a yellow scale figure standing on it
Build a wall segment that's approximately 150-200% as tall as the scale figure.
If you're working in a modern game engine, sizes don't have to be exact -- the sense of proportion is most important to establish here.
If you are blocking out with a modular kit, just place a standard wall module next to the figure.
Texture the wall with a different color from the ground plane. Color and brightness provide important context for understanding what the space is made of, and how these various floor and wall planes relate to each other. If you are afraid of colors affecting your blockout too much, then at least use textures with different shades of gray.
example: added a white wall segment that's twice the height of the scale figure
Copy & paste wall segments to build up more space until you have at least one room or hallway. Some tools feature special "duplicate" or "clone" commands: in Hammer, hold Shift and drag the brush; in UE4, hold Ctrl+Shift and drag the wall object.
Intersections are OK. Messy is OK.
To make a doorway or window, just leave a gap between wall segments, and fill it in later. Entryways and hallways should be at least twice as wide as the scale figure.
example: copy-and-pasted / duplicated more wall segments, based on the first wall

3. Playtest

Do a simple self-playtest: walk around the space, within the game engine, with full player gravity, collision, and speed.
The purpose of the blockout is to experiment. To verify the results of the experiment, you must test the prototype. Do NOT just fly around in the editor view, that won't help you imagine the player experience.
  • Massing. Do the level's shapes make sense? Is it confusing to look at?
  • Metrics. Does the player fit through every door and passage? Do the stairs / ramps work? Can the player jump where they're supposed to jump?
  • Flow. Does movement feel slow or fast, smooth or complex? What type of movement is ideal for your intended design goals?
example GIF: walking around the half-built space in the game engine, playtesting as soon as possible

4. Diverge and iterate

Diverge from original plans and respond to the playtest.
99% of the time, your blockout will not survive a playtest. Rooms will feel awkward, doorways too narrow, the layout too confusing. But this is exactly why we blockout!
Want to rebuild huge sections of your blockout? Go for it. Want to delete an entire room? Do it. Need to split a courtyard into two smaller areas? You have permission.
example: following a layout sketch, more areas blocked out with more scale figures
Keep an open mind about what your playtests and walkarounds are telling you.
Continue adding new scale figures, walls, and floors.
Then playtest again.
example GIF: the original blockout felt too cramped, so what if we widened the space and deleted the walls?

5. Continue iterating

Keep an open mind and continue this cycle of modification + playtesting. Continue developing the blockout. Build, then walk around in it, then modify, then playtest again... and repeat. This design process is called iteration, because we are making new iterations that build off of the strengths of the previous version.
As you gradually build more and more of the level, it may surprise you how much it changes over time. Let the map surprise you.

Common blockout problems

  • (most common) My blockout feels too small / too big.
    • Use more scale figures during construction.
    • Playtest more often and catch scaling problems sooner.
    • Too big? Delete unnecessary rooms and compress what's left.
    • Too small? Expand outermost walls, then expand the center to fill up the new space.
    • Or delete everything and rebuild. It's just a blockout.
  • I have anxiety and stare at the empty level editor screen without making anything.
    • Sketch a layout drawing, and then try to follow that plan.
    • Just blockout one simple room. You can always delete it later. The point is to get rid of the blank page. In drawing, this is "activating the canvas"; in writing, this is a "shitty first draft."
    • Do something else and return to the blockout later.

Example blockouts

"Castle" for Dirty Bomb (Splash Damage)

layout, blockout, and final version of Castle for Dirty Bomb, by Splash Damage ("Blocktober: Dirty Bomb")
Splash Damage level designer Anthony "MassE" Massey designed the map Castle for the competitive multiplayer team shooter Dirty Bomb. Massey took inspiration from twisting medieval streets and typology of the real-life Tower of London, and conceptualized the initial layout drawing (above, left). But note how the resulting blockout (above, center) differs from the layout with fewer curves, more 90 degree angles, and chunkier areas. The layout was just an initial guide. Because this is a multiplayer shooter map, the design team playtested the blockout with a focus on movement and combat metrics:
“The scale of maps is always the hardest aspect to get right. It’s important to plot your main paths and measure these distances; we’re looking for anything between 8 and 12 seconds from spawning to an objective. [...] Anything longer than that and players get frustrated when they respawn and have to run back. On the other hand, if the time is shorter it risks the map feeling too small for 8v8 matches, and can lead to chaotic gameplay. [...] This stage is crucial to map development, but our team operated by a simple rule of thumb; if it feels long, it’s too long."
"Considering [player classes] is the next step. We had to look at combat ranges to allows our entire arsenal to function, [...] while also ensuring variety in combat spaces to allow [different abilities] to be viable (like [an airstrike ability]). In real terms, this means considering the ratio between outdoor and indoor areas, ensuring [characters with outdoor-focused abilities] were viable."

"World's Edge" for Apex Legends (Respawn)

final detailed blockout (left) and final art pass (right) for "World's Edge" map in Apex Legends; blockout by Rodney Reece
Respawn level designer Rodney Reece built the blockout for "World's Edge", a large competitive multiplayer map for first person battle royale game Apex Legends. Notice how the map changed drastically from blockout (left) to art pass (right) in not only theme but also layout and composition.
"Originally the idea was the map was snowy. But art wanted to bring green into the map, and in one of the meetings, Robert Taube suggested what if the Epicenter (then called Frozen Explosion) caused the snow.
A key to being a good designer is being flexible to new ideas. For instance, the Art team came up with The Dome. In my blockmesh, it was a volcano. They pitched it and I adjusted to incorporate the idea. I had to create a new layout for it, but it made it better.
But other times, certain [points of interest] are fun from the beginning. In those situations, I am more stubborn about what can change. Sorting Factory is a good example of that. It's important to identify what's precious and what's flexible in terms of layout. Because it takes a team!"

Against blockouts?

For some projects, the traditional blockout might be less helpful. The experience may depend less on spatial design and more on the art pass. Blockouts can't validate a concept dependent on art or other assets.

Vertical slice for "Firewatch" (Campo Santo)

For the first person narrative exploration game Firewatch (2016), developer Campo Santo wanted to focus on mechanics like walking and talking; the main appeal of the game concept was looking at art passed scenery and listening to voice acted dialogue. Following typical best practices, they first built a blockout to test the viability of these mechanics. However, the blockout did not help them answer any questions about the player experience because the game pacing was fundamentally a narrative design and environment art issue, not so much a level design issue. The traditional blockout process wasn't working.
According to environment artist Jane Ng's account, it wasn't clear whether Firewatch would "work" as an experience until they skipped the blockout process and instead completed a vertical slice prototype with an art passed environment and near-final dialogue.
"Greyboxing did not answer any of the important questions" and other slides from "Making the World of Firewatch" by Jane Ng at GDC 2016

Location scouting for "Untitled Goose Game" (House House)

For the top-down third person stealth puzzle game Untitled Goose Game, developer House House sought to create an authentic-feeling British village in 3D. Level designer Jake Strasser had never been in the UK, so blocked out the initial level with occasional use of photo reference. However, this blockout-first approach required Strasser to fill-in gaps from his imagination -- and because he didn't have a British imagination, these gaps often felt implausible or inauthentic in subtle ways, counter to their intent. The traditional blockout process wasn't working.
So instead, Strasser tried a research-first "location scouting" approach. He went on an exhaustive virtual tour of various UK villages, taking lots of photos from Google Street View. After recreating several village streets in-game, Strasser finally pin-pointed what type of structure suited the game's needs, and settled on an unusual side street layout based on Pump Street in the village of Orford. Here, blockout was less about building a space, and more about discovering a space.
"It started feeling more like a unique place with its own quirks and history"... from "Google Maps, Not Grayboxes: Digital Location Scouting for Untitled Goose Game" for GDC 2021 by Jake Strasser

To review

A blockout is a simple but playable "rough draft" level with minimal detail. We keep it simple and blocky so that we can easily change it.
You can build a blockout with primitives, brushes, modular kit, sculpting, or splines. The best technique will depend on your engine and project, or you can combine multiple techniques.
How to blockout:
  1. 1.
    Sketch a layout, even a simple one
  2. 2.
    Add a ground plane, scale figures, and walls.
  3. 3.
    Playtest immediately; does it feel OK to walk around? You need to know now.
  4. 4.
    Diverge from your original plan, iterate and playtest again
  5. 5.
    Repeat step 4.
The most common problem is scale, especially for beginners. Playtesting the blockout in-game is the best way to know if it feels too big or too small.
Blockouts might be less helpful for some projects like single player art-dependent narrative levels.

Now what?

More about blockouts

Last modified 1yr ago