What is Ostraplan?

Ostraplan is an out-of-game ship planner for Ostranauts (Blue Bottle Games).

It lets you drag every buildable part (incl. loaded mods) onto the game's exact tile grid, validated live with the game's own rules, so you know a design works before you lay a tile in-game.

The Goal: if you can build it in Ostraplan, you can build it in Ostranauts, and it will be a valid ship.

This was achieved by porting the game's validation logic as best I can. That includes, placement rules, sockets, airtightness, room certification, and the Ship Rating.

Ostraplan is a sibling tool to Ostrasort and I encourage you to use both. Ostrasort lets you register your modded ships as a valid mod as well generally managing mod conflicts and loading order.

--- ---

Licence & Disclaimer(s)

Ostraplan is a fan-made tool, not affiliated with or endorsed by Blue Bottle Games. Ostranauts and all its data and art are © Blue Bottle Games.

Ostraplan ships none of it, reading everything from your own install at runtime.

Please support and buy the game: https://store.steampowered.com/app/1022980/Ostranauts/.

You will not be able to use Ostraplan without a valid copy of the game on your machine.

No Warranty

I provide Ostraplan as-is, with no warranty of any kind. It can write to your save files, so back them up first. Use it at your own risk. I am not responsible if it breaks your game/save or causes your ship to become sentient.

Active Development

There will 100% be bugs and I will do my best to fix them in a timely manner but this is a free opensource tool so please be patient and bear with me, I also have a day job!

Please report your bugs here on the repo's Issues tracker.

Features

Design

• Every buildable part in one palette — the game's eight tabs (HULL · HVAC · POWR · SENS · CTRL · FURN · APPS · MISC), searchable, drawn with the real 16 px sprites.
• Build on the real grid — drag-and-drop with game-accurate autotiling, R to rotate, crisp pixel-art zoom/pan, and plan-view rotation.
• A full editing suite — drag-paint, box/hollow fill, symmetry mirror, flood-select, "Replace with…", ship-wide re-skin, group rotate, group flip (H / Shift+H), copy/paste, and unbounded undo/redo.
• Bill of materials — install-kit counts for the whole ship or a selection.
• Zones — draw and manage the game's crew/trade zones (Haul, Barter, Forbid, and content trigger zones): paint them with the same tools as parts, and they round-trip faithfully through export and save write-back instead of being dropped or shifted onto the wrong tiles.

Validate

• Live Validation — you can't place what the game would refuse; the ghost glows green/red with the failing tiles and the reason, and building past an airlock's mating face is blocked.
• Rooms, airtightness & Ship Rating — flood-fill compartments, room certification, and the six-slot rating.
• Law report — every problem in one place, tracing air leaks to the exact unsealed tile.

Import & export

• Import a template — any core or modded ship.
• Import your ship from a save — pull your live layout out of a save game.
• Edit your live ship — import it, redesign, and write it back into a copy of the save, with crew, cargo, position and identity preserved (the original untouched).
• Export as a mod — a spawnable local mod in the game's own data/ships shape, rooms and rating precomputed.

Mod-aware

Resolves your loading_order.json exactly like the game, so modded parts appear in the palette. A design records the mods it needs; open it without them and it stays read-only until you enable them, so nothing is silently lost.

Plus PNG snapshots, light/dark theming, and an optional update check.

What Ostraplan won't do

Ostraplan validates the build it's a planner, not a simulator. It won't:

• Simulate power, gas, thermal, or crew pathing (the game authors no per-device rates, so an honest budget would need a full network sim);
• Model economy beyond the bill of materials;
• Edit more than one ship per document;
• Write loading_order.json (registration stays with Ostrasort), or publish to the Workshop (export makes a local mod, you upload in-game);
• (Ostrasort will not) run anywhere but on Windows.

Read-only first: it never touches your game install, saves, or loading_order.json by default.

Save-editing features want to create a copy by default unless you opt into an in-place edit, which then creates a backup anyway (because I care about you).

Quick start

Download the latest Ostraplan-vX.Y.Z.exe from the Releases page and double-click it. It's a self-contained executable and if you don't trust me you can build it yourself by following the instructions below.

Requirements: Windows, and a local Ostranauts install. Ostraplan finds the game automatically if its installed and reads its data and sprites at runtime. Without this, Ostraplan just doesn't work.

No game assets are distributed with the tool.

Building from source

Needs the .NET 10 SDK.

dotnet run --project src\Ostraplan.App     # launch
.\test.ps1                                 # run the test suite (most tests are game-free)
.\test.ps1 -Filter Rooms                   # run a subset by name
.\publish.ps1                              # build publish\Ostraplan.exe (self-contained)

Most tests run without the game; the ones that need a local Ostranauts install report as skipped (never a false pass) when it's absent. See docs/TESTING.md.

Documentation

• docs/usage.md — how to use it, start to finish.
• CHANGELOG.md — what shipped, version by version.
• docs/SPEC.md — design, scope, the .oplan format, and the roadmap.
• docs/GAME-INTERNALS.md — the reverse-engineering reference: what's ported, deferred, and excluded.
• docs/TESTING.md — how the test suite is structured (game-free vs game-gated), how to run it, and how to add a test.