Custom Maps (Build Map)

Straight answer: there is no official feature called a "build map." Building your own map is a community affair — the CustomMapLoader mod loads player-made maps, which are "mods that also contain the pngs the game uses to load the map." Here is the workflow.

The Tool: CustomMapLoader (Community Mod)

CustomMapLoader (CML) is "a mod for Sandustry that loads in custom maps," made by GitHub user Electric131 — a community tool, not an official Lantto Games product. The game itself is "MADE FOR MODDING" per its store page, including "hand-crafted maps."

In CML's terms, a custom map is a mod package: the PNG images the game reads as terrain, plus metadata files. Distribution runs through the Fluxloader site (fluxloader.app); the Steam Workshop hub also hosts "Mods and maps for Sandustry."

The Workflow

• 1. Start from an existing Fluxloader mod as a base, or use the "Create Mod" button in the UI.
• 2. In the mod's modinfo.json, add the map tag and declare the CML version dependency (the docs suggest ^x.x.x pinned to the CML version you build against).
• 3. Author the map itself — the CML wiki splits this across four pages: Map PNGs, Map Colors, Map Meta, and Map Scripting.
• 4. Before uploading: confirm the map tag is present ("otherwise the CML won't recognize it"), mark CML and any used mods as dependencies, and test-load in game.
• 5. Zip the whole mod folder and upload to fluxloader.app for others to download and play.

Map-Maker Tips From the Docs

• Find the player's Y coordinate manually: run fluxloaderAPI.gameInstance.state.store.player.y in the console.
• Or compute it from the map image: (pixel_y × 4) − 30 gives the player's y when standing on that pixel.
• The fog texture can be auto-generated from the blueprint PNG using the author's companion tool, Sandustry Light Spreader.

Version Caveats (Read Before Building)

The documentation and releases disagree: the CML wiki banner says "up to date as of v4.1.3," but the newest GitHub release is v3.1.2 (March 2025) — v4.x apparently ships through fluxloader.app rather than GitHub. Major CML version changes are breaking, so maps must be updated when CML majors change.

The step-by-step docs were last edited January 15, 2026 — before the August 2026 Early Access release. Whether the workflow works unchanged against the current build is unverified; also unverified is whether custom maps can be published directly through Steam Workshop.