A sandboxels mod (https://sandboxels.r74n.com)

rainbow_slime.js

// rainbow_slime_min.js
// Minimal Sandboxels mod: adds a simple "Rainbow Slime" liquid element.
// Purpose: minimum working example — no per-pixel color writes, no helper wrappers.

(function() {
  if (typeof elements === "undefined") {
    console.warn("rainbow_slime_min.js: Sandboxels globals not found. Load this as a mod inside Sandboxels.");
    return;
  }

  // avoid overwriting existing elements
  if (elements.rainbow_slime) {
    console.log("rainbow_slime_min.js: element 'rainbow_slime' already exists — skipping registration.");
    return;
  }

  elements.rainbow_slime = {
    name: "Rainbow Slime",
    // static color only (engine-friendly hex string).
    // If your build requires an object {r,g,b}, try {r:255,g:59,b:48} instead.
    color: "#FF3B30",
    category: "liquids",

    // Basic physical properties (reasonable defaults)
    density: 1000,
    conductivity: 0.05,
    viscosity: 0.6,
    tempHigh: 1000,
    stateHigh: "steam",
    tempLow: -273,
    stateLow: null,

    // Simple liquid-like behavior expressed as a behavior string.
    // This avoids custom tick() code that could call engine internals differently across builds.
    // The string below makes it fall, flow, and have a tiny chance to 'stay' (so it doesn't vanish).
    behavior: [
      "XX|CR:5|XX",
      "M2|CH:0|M2",
      "XX|FX:0|XX"
    ].join(";"),

    // Basic reaction example (harmless)
    reactions: {
      "water": { elem1: "water", elem2: "rainbow_slime", result1: "rainbow_slime", result2: "water", chance: 0.25 }
    },

    info: "A simple colorful slime. (Minimal example — no dynamic color or particles.)"
  };

  // Add a residue element if none exists (simple solid)
  if (!elements.slime_residue) {
    elements.slime_residue = {
      name: "Slime Residue",
      color: "#9B59B6",
      category: "solids",
      behavior: "XX|CR:1|XX",
      density: 800,
      tempHigh: 1000,
      stateHigh: "steam",
      info: "Sticky residue left by Rainbow Slime."
    };
  }

  console.log("rainbow_slime_min.js loaded: rainbow_slime + slime_residue registered.");
})();