Oxygen Not Included: Best settings.json for Gas Simulation

The primary goal for Oxygen Not Included is Entropy Reduction. The game slows down because it has to calculate heat transfer and pressure equalizations between different gas types (e.g., Oxygen touching Chlorine). This configuration focuses on utilizing the Fast Track mod (a community standard for optimization) and manual file tweaks to simplify how the game handles these constant updates.

Hardware Compatibility & Expectations

• The CPU Bottleneck: ONI is heavily dependent on single-core speed. Even a 16-core CPU will struggle if the individual cores are slow.
• The “L3 Cache” Advantage: This game performs exceptionally well on CPUs with large caches (like the AMD Ryzen X3D series), as it stores the massive grid-data more efficiently.
• RAM Latency: Since the game constantly scans the map grid, low-latency RAM (CL14/CL16) provides a noticeable boost in “Ticks Per Second” (TPS).

File Location

For technical settings and mod-driven simulation tweaks, you need to look in: %USERPROFILE%\Documents\Klei\OxygenNotIncluded\settings.json (Note: This file may be generated by mods like Fast Track or DGSM).

The primary game settings are in: %USERPROFILE%\Documents\Klei\OxygenNotIncluded\kplayerprefs.yaml

Best Settings for Gas Simulation Efficiency

To improve gas simulation, you must combine .yaml tweaks with the Fast Track mod configuration.

1. kplayerprefs.yaml (Graphics/Engine Overhead)

Lowering the UI and rendering overhead frees up CPU cycles for the gas grid:

# Set these to reduce rendering lag
FrameRateCap: 60              # Capping FPS to 60 prevents the GPU from stealing CPU time
WaitVsync: 1                  # Essential for stable frame pacing in simulation games
ResolutionWidth: 1920
ResolutionHeight: 1080
UIScale: 1.0                  # High UI scaling on 4K monitors can lag the overlay updates

2. Fast Track Mod (The “Real” Simulation Fix)

Fast Track (available on the Klei Forums/GitHub) adds a settings.json in your mods folder. Ensure these performance flags are active:

{
  "OptimizeAtmosphere": true,     // Reduces the frequency of pressure equalization checks
  "ParallelPathfinding": true,    // Offloads Dupe movement from the gas simulation thread
  "LowPriorityCritters": true,    // Reduces the AI "Tick" for animals
  "ReduceRadiationUpdates": true  // (Spaced Out DLC) Significantly saves CPU cycles
}

Strategy for “Gas Lag” Prevention

Config files can only do so much; your Base Design is the “hardware” of the simulation.

• The Vacuum Barrier: Seal off unused areas of the map and vacuum them out. A vacuum tile requires zero calculations, whereas a tile full of gas requires constant temperature and pressure checks.
• Element Sorting: Do not let different gases mix. Use a “Water Lock” to keep your Oxygen base separate from the Chlorine/Hydrogen biomes. Each “contact point” between two different gas types is a math equation the CPU has to solve every tick.
• Tile Overlays: Avoid using too many “Mesh Tiles” or “Airflow Tiles” globally. They increase the number of paths the gas can take, forcing the engine to calculate more potential movements.

Essential Optimization Mods

Mod Name	Purpose	Impact
Fast Track	Complete engine rewrite for performance.	40-60% FPS Increase.
GasOverlay	Replaces the useless vanilla overlay with a color-coded one.	Visual Clarity.
Bigger Camera Zoom Out	Allows you to see the map, but warning: zooming out too far increases lag.	Navigation.
No Sensor Idle	Prevents sensors from checking every tick when not needed.	Logic Stability.

Troubleshooting & Common Fixes

• Stuttering Every Morning: This is the “Daily Autosave.” You can increase the interval between saves in the game options to every 5 or 10 cycles.
• Lag During “Gas Overlay”: The gas overlay is very heavy. Toggle it only when necessary. If it’s too slow, ensure your GPU drivers are updated to handle the transparency layers.
• “Pathfinding” Spikes: If you have 20+ Duplicants, the game will stutter. Limit your colony to 8-12 Duplicants for long-term (2000+ cycle) performance.

Frequently Asked Questions (FAQ)

Conclusion and Expected Results

By combining the Fast Track mod’s optimization with a disciplined approach to Vacuum Sealing, you are attacking ONI’s performance issues at the source. You can expect a significant reduction in “Late-Game Sluggishness,” instant response when switching between asteroid views, and the thermal stability needed to reach Cycle 3000+.