Oxygen Not Included: Best settings.json for Liquid Physics

In 2026, the meta for performance has shifted toward the Fast Track mod logic, which optimizes how the game handles “Cellular Updates.” Manually, you can adjust the kplayerprefs.yaml to reduce the visual overhead of these physics, though the heaviest lifting is done through in-game “Engineering” to simplify the simulation’s pathing.

File Path

The primary configuration file for Oxygen Not Included is not a .json but a .yaml file located in your Klei user folder.

%USERPROFILE%\Documents\Klei\OxygenNotIncluded\kplayerprefs.yaml

Technical Note: This file handles the interface and general engine flags. For deep physics changes, the game relies on Mod Injection (like Fast Track) because the physics engine is compiled C# code within the game’s .dll files.

Optimized Configuration Flags (kplayerprefs.yaml)

Adjust these lines to ensure your GPU isn’t competing with the CPU’s physics simulation for resources.

Parameter	Recommended Value	Technical Purpose
FrameCap	60	Capping FPS prevents the CPU from over-scheduling frames over physics ticks.
LowResTextures	false	(Keep False) Low-res textures don’t help physics; they just make the UI blurry.
VSync	0	Disable in-game VSync; use “Fast” VSync in your GPU control panel to reduce stutter.

# Add or modify these lines in kplayerprefs.yaml
FrameCap: 60
VSync: 0

HowTo: Engineering “Lag-Free” Liquid Systems

Since you cannot easily edit a “Physics JSON,” you must engineer your base on GameEngineer.net to minimize the simulation workload:

1. Vacuum Sealing: The game calculates temperature for every tile. By vacuuming out unused areas of the map, you change the tile state to “Null,” which eliminates the CPU’s need to calculate temperature transfer or gas/liquid movement in that space.
2. Infinite Liquid Storage: Use the “Compressor” method (stacking a small amount of a different liquid over a vent) to store thousands of tons in a single tile. The game calculates physics for one tile instead of hundreds, drastically increasing TPS (Ticks Per Second).
3. The “Pipe Bridge” Rule: Never use junctions (T-sections) in your plumbing. Every junction forces the game to perform a “Pathfinding” check for every packet of liquid. Using Liquid Bridges to merge or split lines forces the packet logic into a pre-determined path, skipping the calculation.
4. Debris Consolidation: Sweep all debris into a single “Infinite Storage” tile. Each individual piece of copper ore on the ground is an object with its own temperature physics. When they are in a single stack, they are treated as one calculation.
5. Fast Track Mod (Mandatory): In 2026, the Fast Track mod is the only way to “multi-thread” certain parts of the liquid and gas simulation. It can increase your late-game FPS from 15 to 45.

Technical Explanation: Cellular Automata and State Changes

Oxygen Not Included uses a Grid-Based Simulation. Every tick, the engine asks: “Is the liquid in Cell A heavier than the gas in Cell B? If yes, swap them.” In a $256 \times 384$ map, that is nearly $100,000$ checks every fraction of a second.

By using Liquid Bridges, you are essentially “hard-coding” the answer to those checks. The bridge tells the engine exactly where the packet goes, bypassing the neighbor-check logic. Similarly, reducing the variety of liquids (e.g., sticking to just Water and Petroleum) reduces the number of “Interaction Lookups” the engine has to perform when two elements touch.