About the Game
WARNING! THIS GAME IS IN EARLY ACCESS. IT IS BUGGY AND COMPUTE HEAVY. PLAYERS MAY FACE POTENTIAL BUGS, FREEZES, AND CRASHES.
WHILE THIS GAME UTILIZES WEBGPU and ELECTRON, LINUX/PROTON/MACOS ARE NOT OFFICIALLY SUPPORTED YET.
I UNDERSTAND THAT THE AI GENERATED CONTENT IS UNAPPEALING AND AM HEAVILY FOCUSED ON ADDRESSING THIS ISSUE.
THERE IS AN ACTIVE DISCORD COMMUNITY, PLEASE JOIN IF YOU'D LIKE TO PARTICIPATE IN ITS DEVELOPMENT.
NUCLEAR DESIGN BUREAU is a hardcore sandbox engineering game where you design and test nuclear devices.
You are a junior engineer at the Kurchatov Institute. The State gives you a target and a warehouse full of dangerous materials. Some directives limit what you are allowed to use. Your job is to build a device that does what the directive asks.
This game is built in the open. The campaign, the physics and the tools change based on what players build, where they get stuck, and what they ask for. That is the whole reason it is in Early Access.
HOW IT WORKS
- Receive a directive: Technical requirements and constraints, with material limits on some jobs.
- Measure it by hand: The criticality lab is first person. Set the core in its cradle, lower the beryllium reflector onto it, and watch the counter on the wall while the live k estimate climbs toward one. Push it too far and the dose lands on your hands, not on a number.
- Design: Paint materials straight onto the blueprint grid. Build the primary, the casing, and the supporting systems.
- Simulate: Hit the red button and run full detonation physics in real time.
- Refine: If it fizzles, fails, or wastes material, work out why and change it.
CORE FEATURES
- Physics-Driven Simulation: Shockwaves, heat, radiation, and chain-reaction behavior are modeled in real time.
- Criticality Lab: A first person room where you handle the real parts. Live Monte Carlo k-effective, a wall counter that lags the way the instrument actually would, and radiation exposure that shows on the operator instead of in a readout.
- Detonation Viewer: Observe detonations as they unfold, with live visual feedback on blast behavior.
- Campaign Directives: Structured mission progression with technical goals and constraints.
- Sandbox Mode: Unlimited experimentation with full design freedom.
- Iterative Engineering Loop: Build, test, diagnose, and optimize.
EARLY ACCESS STATUS (CURRENT BUILD)
The current Early Access build is playable end to end and includes the core gameplay loop:
- Design -> Simulate -> Detonate -> Refine
- The criticality lab
- Sandbox mode
- Campaign directives
- Save/load systems with ongoing stability improvements
This is an active development build. Expect balance changes, physics work, and campaign iteration during Early Access.
EARLY ACCESS ROADMAP (SUBJECT TO CHANGE)
Physics and Simulation
- Refining the detonation viewer (better shockwaves, damage radius and thermal radiation modeling, destructible buildings and targets)
- Finer grid resolution for stronger PCs and GPUs
- More to do in the criticality lab
Campaign and Content
- Expanding the campaign with unique challenges
- Many more directives/missions
- Voiced campaign
- Additional bomb concepts (high-radiation designs, clean bombs, neutron bombs)
- More advanced materials
Presentation and Audio
- More music tracks
Community and Meta
- Public leaderboard
- Statistics on every campaign directive, so you can compare how efficient your design was against everyone else's
DEVELOPMENT APPROACH
Design. Simulate. Detonate.
Early Access is where this game gets shaped in public. What players build, where they get stuck, and what they ask for decides what gets worked on next. Most of the day to day happens on Discord.
"The atom is not a soldier, Comrade. It is a force of nature. We merely tell it where to go."
Screenshots
12 imagesVersion Information
Steam Patch Notes
Official update history
Changelog:
Big designs speedup. 2nd stage burn should be faster
Dt crash fix, extremely large DT volumes being compressed may still cause problems
Yield card in canvas doesn't stretch with the canvas anymore
notices on canvas stay visible when zoomed in
telemetry units moved to be beside value and not under it
changed DT ice message in campaign
low pc specification warning uses recommended specs now
fixed bug for first mission not advancing after moving dialog box
Previous build is on "previous branch" on steam
Changelog:
PU and U235 resist compression more so yields will change
Fixed single pixel microbombs
Fixed sim speed changing yields
Fixed devises with more than 8 fissile clusters fizzling
fixed neutron leaking out of LID and DU too fast
fixed hot gas not expanding
fixed single particles slowing down or stopping designs
foam should not be as slow anymore
fixed temps and xray readouts reading impossible values
xray chart now shows xrays that have escaped the the device
fusion yield now shows percentage of fusion fuel burned
fixed sim not working after a single broken simulation
added warning for extremely large fissile masses attempting to be simulated.
fixed DT gen not firing on auto targeting
fixed slowdown after neutron firing overrides speed setting
campaign text rewritten
RDS-4 directive yield requirement changed to 15kt
fixed missions only counting if accept was pressed right before a shot
Directive card redone
fixed scroll covering the accept button
first directing now explains that you have to press detonate twice
Added the shape's real size in cm to the draw tooltip.
The board you are working on is saved and comes back after a restart.
Transfer is now called SHARE.
Added Clear all marks and delete under the pointer to the board's right-click menu. The menu lists every tool.
Added Clear guides to the Guide tool.
Radial, Guide and Select show their help.
Added Mirror new points to the Curve tool.
Fixed Hole X and Hole Y making a hole twice the size entered.
Fixed rotated rectangles landing off the grid.
Fixed knobs needing three wheel notches per step.
Added Fill air only to Star Lens and Radial.
Fixed the board jumping or flashing black when switching tools. Added a key to fold the tool options row and a setting to keep it open.
Fixed Ctrl+Z undoing several steps at once and held arrow keys moving a selection too far.
The board draws at full resolution on 1440p and 4K screens.
Fixed the placement tooltip leaving a ghost behind the pointer.
Fixed low-contrast text and the selected speed being hard to see.
Fixed material being placeable after DETONATE was pressed.
Fixed WASD in the detonation viewer acting one key late.
Graphs keep drawing while the window is unfocused.
Fixed the yield readout switching to Mt too early.
A tested design can be saved under a new name.
Long Radio Moscow song titles scroll.
The interface fonts and paper textures ship with the game. Nothing is downloaded at start.
The Kurchatov Institute now warns when your computer is below the recommended specs.
The shot readout, graphs, tool bar and detonation viewer redraw less during a shot.
Update "Helium" is still in the works
coming soon.
Steam Workshop integration, 3d museum and new challenges**
Last version is on previous build in case your game completely breaks
proton users please file a bug report if the sim is crashing again, I will try to fix it. Make sure to include logs
Missing buttons UI bug fixed
Update "Hydrogen" is out!
We recently hit 10k players! Thank you all for the support and feedback once again. We could not have done this without you all.
You told us the old interface was hard to use, so we rebuilt it from the ground up.
Changelog:
Physics
- Depth of sim increased to 5 cm from 2.5 cm.
- Critical masses updated to be more correct.
- New, more accurate and faster neutronics.
- Big rebalancing and yield changes have occurred, so many designs will break or have wildly different yields.
- Hydro now has a per-particle delta t, so there should be speed gains in large, very hot designs.
- Campaign has been reworked slightly for different yields, and DT ice has been removed. LiD is now the only fusion fuel allowed in the campaign.
New UI/UX
- New look overhaul with different buttons, windows, and textures.
- New telemetry graphs.
- Custom themes in settings (WIP).
- Zooming on graphs.
- Comparing runs.
- Easy switching from campaign to sandbox.
- New material section and hotbar with hotkeys.
- New tool section with hotkeys.
- New shot panel.
- New settings menu.
- Right-click menu with options.
- And many more QOL tweaks.
Please test your LID designs and have fun!
Right-click Nuclear Design Bureau in your Steam Library → Properties → Game Versions & Betas → select the experimental "sparkplug" branch, then update your game
[img src="{STEAM_CLAN_IMAGE}/45893015/cd01b642581f05db8438c99c0a7d5be10f2df338.png"][img src="{STEAM_CLAN_IMAGE}/45893015/9b49d48eac6345a91bc79ca294d618c1bfd56bda.png"]
Added simulation speed buttons: 1, 1/2, 1/4 and 1/10 for those with super gpu's..
Fixed Space placement after adjusting shape knobs.
Fixed large designs failing to save or copy.
Fixed proton menu and drop down problems hopefully
Fixed incorrect sizes in selection tooltips and the archive. Existing archive entries update automatically.
Stopped scrolling from changing knobs unless they’re selected.
Added a warning before replacing a design through the dossier.
Fixed graph tooltip overlap and graph dragging/resizing at different UI scales.
Fixed graphs covering the controls in smaller windows.
Reset and Clear now keep your camera position and zoom. Press F to fit the board.
Fixed rotated rectangle previews and drawing alignment after changing UI scale.
Fixed Steam Cloud syncing for settings, achievements and larger saves.
Fixed a tutorial retry getting stuck after Reset.
Capped the 3D viewer at 60 FPS and paused rendering while hidden.
Disabled the Steam overlay by default on Windows to prevent crashes temporarily.
Good news on the LID front, its working finally. I'm hoping to get it out in the next patch tomorrow (HOPEFULLY)
I might do an experimental branch considering it will be a big physics change, the neutronics is changing bigtime.
Also I'm probably going to remove DT ice once LID works, and replace it with liquid deuterium, DT ice is not a practical fuel for this game.
1. Directive 1-2 no longer sits silent after DETONATE; the lesson pauses when the yield settles.
2. Directive 1-2: two-cell relief bore in the gun barrel, and a step that teaches the eraser.
3. Gunpowder no longer fires on its own. Ignition starts at the primer.
4. All campaign directives, the Field Manual, material descriptions, achievements and settings text were rewritten.
5. Field Manual diagrams replaced: seven captures from real shots, four public-domain plates.
6. Settings no longer show window-debugging notes.
7. A challenge finished with RESET now completes.
8. A failed safety-check roll no longer refuses the same drawing until restart. DETONATE re-runs the check.
9. RESET no longer clears the telemetry graphs.
10. Readouts mark thousands with a lowercase k, so 212,000 K no longer prints as 212.0K.
11. The time label on a filling graph sits under the last sample.
12. Releasing the mouse over a side panel no longer breaks drawing, panning or selection.
13. A design whose fissile mass equals the budget exactly is accepted.
14. The Fizzle achievement no longer unlocks on an abandoned run, and unlocks on a real fizzle at once.
15. Saving over an existing name asks first. An empty name no longer locks the field.
16. Leaving an unsaved drawing for Stand FKBN, Campaign or Sandbox asks first.
17. Shape tools gained a fill-empty-cells-only switch.
18. Erasing a placed curve no longer leaves a ghost outline.
19. The curve tool draws about the cell under the cursor.
20. The k warning outline follows the camera.
21. The tutorial pointer no longer lands on the buttons it points at.
22. Workspace columns are chosen from post-zoom width; the rail is no longer clipped at 1920x1080.
23. The resolution list on small displays explains which presets fit and offers borderless.
24. The screen-edge vignette can be turned off.
25. Volume sliders step by 0.01, and the Windows media flyout stays closed while the radio plays.
26. Yield units read t, kt and Mt.
27. Screw heads and grille panels on the tool rack and the radio render.
28. The Safety Interlock warning keeps its buttons on screen.
29. The settings button can no longer be scrolled off the screen.
30. Pasting a design string into the settings import says where it belongs.
31. Critical Mass, First Light and the Proving Ground stamp accept placements up to 3 cells off.
32. First Light pauses at 40 kt instead of a gate the block cannot reach.
33. Space commits a rectangle mid-drag, and the early steps name the shortcut.
34. Loading a mission resets the camera to the gold guide.
35. Directive requirements show placed amounts in kilograms and cells.
36. The Tamper gained a retime-the-generator step and a hint with exact dimensions.
37. A Sandbox design carried into Campaign is refused at DETONATE until its locked materials are removed.
38. Quit to Desktop sits at the bottom of Settings beside Done, without scrolling.
39. Wipe All Data asks twice.
star lens fix
Hopefully the many alt tab copies is finally fixed, it was windows making ghosts when alt tabbing and the application was unresponsive.
circle and ellipse dont have the pointy pixels now same for star lens
directive 2-2 (Compression Qualification) accepts the core, drive and lens again with the new shapes.
directive 1-3 now says "Set Timer to 6000 microseconds, not 6".
detonation viewer camera now drags of the ground
new tools
circle arc section
rectangle trapezoid option
and guide tool for making lines
Current Release
Build 25687655
Uploaded Oct 10, 2026
System Requirements
How to Install
Nuclear Design Bureau.exe to play
Troubleshooting tips
• Run Redist/_CommonRedist installers if game won't start
• Add folder to Windows Defender exclusions
• Run as administrator
Download
Direct link available
Needed when extracting (WinRAR / 7-Zip) — not a site login.
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