Custom Gas Types

Custom Gas Types

A chemical-warfare mod and a modding framework. Five hand-made gas agents with their own hidden IED traps and mortar shells, a full research tree, and drug-lab production - plus an XML framework that lets any mod add brand-new gas types to RimWorld 1.6, which the base game otherwise hard-codes to just four. Custom gases behave exactly like vanilla gas: they billow out cell by cell, drift through open doors, are stopped by walls, equalize through vents, and dissipate over time - faster in the open, much faster in vacuum.

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The Gases

AgentColourLethal?Countered by Tear GasPinkish-redNoAny respirator Nitrous OxideTealNoAny respirator Mustard GasYellowYes (slow)Respirator + sealed suit HalothaneDark blueOn overdoseAny respirator VX Nerve AgentDark purpleYes (fast)Respirator + sealed suit Tear Gas - A pinkish-red cloud of CS riot agent. Blinds and chokes anyone inside; enough exposure drops raiders through pain shock. Non-lethal, wears off in a few hours. Fully blocked by a proper gas mask. Nitrous Oxide - A teal cloud of laughing gas. Targets get lightheaded and giggly (yes, there's a mood buff), then stumble, then drop unconscious - fully anesthetized and pain-free. The humane way to fill your prison. Non-lethal. Mustard Gas - A heavy yellow blister agent that lingers far longer than any other gas. It chemically burns skin, eyes and lungs; survivors face days of painful recovery, and untreated severe exposure kills. A mask alone only helps so much - it attacks exposed skin too. Halothane - A dark blue anesthetic vapor. Sedates and knocks out anyone who breathes it. Careful: victims left lying in the cloud will overdose and die. Fully blocked by a proper gas mask. VX Nerve Agent - A dark purple aerosol and the deadliest thing you can synthesize. Twitching, convulsions, paralysis, respiratory failure - death in minutes at full concentration. Persistent area denial. A mask alone only halves the exposure, and survivors need intensive tending.

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How It Works

1. Research the new Gas Warfare tab. Each agent has its own production node - tear gas and nitrous oxide are cheap Industrial techs, mustard needs biofuel refining, while halothane and VX are Spacer-tier and want a multi-analyzer.
2. Synthesize canisters at the drug lab in batches of five, using the Intellectual skill (VX demands a true expert). Canisters are inert items on their own... unless something shoots or burns them, so store them somewhere safe.
3. Deploy two ways, each from a canister, steel and a bursting charge:
   • Gas IEDs (research Weaponized Gas IEDs) - hidden traps from the Security menu that trigger on touch or bullet impact.
   • Gas mortar shells (research Weaponized Gas Shells) - crafted at the machining table and fired from mortars to blanket a distant target in gas. With Combat Extended installed they become real 81mm mortar shells, selectable in the mortar's ammo menu.

Protection - two realistic layers

• Respirators (gas masks, sealed helmets, tox-immune genes) block the gases you breathe: tear gas, nitrous oxide, halothane. A proper filtered mask blocks them completely; a makeshift/improvised mask only cuts the dose.
• Sealed body suits stop contact agents from burning exposed skin.

Blister and nerve agents (mustard, VX) attack skin as well as lungs, so a mask alone only partly protects - for full immunity you need a mask and a sealed suit, or a one-piece hazmat/NBC suit. Mechanoids don't breathe and ignore all of it.

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Mod Settings

• Realistic gas colours (off by default) - recolours every gas cloud to resemble its real-world counterpart: mustard gas turns dark yellow, VX a faint amber, and colourless agents (nitrous oxide, halothane, tear smoke) are drawn white so they stay visible. Toggles live, and it also recolours the Bloat add-on's gases.

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Compatibility

Requirements

• RimWorld 1.6
• Harmony
• No DLC required. Gas masks and tox-resistant genes integrate with Royalty/Biotech if you own them, but nothing is mandatory.

Apparel gas protection (auto-detected - none of these mods are required, support just switches on if they're present):

• Combat Extended - the proper gas mask and sealed plate/night-vision helmets give full respirator protection; the improvised gas mask gives partial protection.
• Dubs Rimatomics - MOPP and radiation masks act as respirators; MOPP and radiation suits seal the skin. Wear a mask and a suit together for full immunity.
• The Dead Man's Switch - the hazard suit is a one-piece sealed ensemble: full protection on its own.
• Any other mod whose apparel uses the vanilla tox-gas-immunity flag (including the vanilla/Biotech gas mask) - and any tox-immune gene - works automatically.

Other mod interactions

• Combat Extended - gas IEDs and shells automatically use FSX as their bursting charge, and the gas mortar shells become native CE 81mm ammo (craftable, loadable, and selectable in the mortar's ammo menu). Without CE, they're vanilla mortar shells instead.

Add-ons

• Custom Gas Types - Bloat - adds four heavier agents: white phosphorus, phosgene oxime, hostile nanobots (which destroy bionics), and chloropicrin.

Saves & performance

• Safe to add to an existing save. Removing mid-save isn't recommended (leftover canisters/traps).
• Custom gases run on their own optimized per-map grid and never touch the vanilla gas system, so the performance impact is minimal.

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Tips

• Nitrous oxide and halothane are the non-lethal capture tools - flood a breach and pick up the sleepers. Don't leave pawns in halothane too long or they'll overdose.
• Mustard and VX are persistent area denial - they linger, so use them to seal a chokepoint you don't intend to walk through.
• Gas drifts and seeps through doors. Vent it out of your own base before sending colonists in.
• Give your own colonists a gas mask (and a sealed suit vs. mustard/VX) before defending a gassed killbox.

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For Modders

Custom Gas Types is a full framework as well as a mod. You can add your own gas types, gas-releasing explosions (IEDs, shells, grenades), weaponisation chains, and protective apparel or bionics - mostly in pure XML, no C# required. There's a complete field reference, a two-layer protection guide, and a copy-paste worked example. ➡ Modding Wiki: https://rentry.co/bk4x7c6u Dev mode also includes tools to spawn and clear every custom gas for testing.

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FAQ

Do raiders avoid the gas? No - they walk right into your kill zone. That's the point. Does it affect animals and insects? Yes, anything that breathes. Mechanoids are immune. Can I add it to an existing colony? Yes - it's save-safe. Mortar shells? Yes - research Weaponized Gas Shells to craft gas mortar shells (native 81mm ammo under Combat Extended). Grenades are still on the wishlist; the framework already supports them.