Blitz3d Decomp

CommunityPopular

rehan-remade

blitz3d-decomp

Decompile a Blitz3D game to readable Blitz source with B3DDecomp and port what it does to another engine. Covers SCP - Containment Breach-era and other .bb games, B3DDecomp, Blitz3D runtime behaviour (fixed tick, Animate, CurveValue, Euler angles, quaternions, Rnd), animated .b3d models (viewmodels with bones and keyframes) into Roblox, and where to stop (builds protected against decompiling, games and assets the user has no rights to). Use when a Blitz3D game's code or animated models are needed.

Overview

Publisher	rehan-remade
Repository	`universal-modder`
Skill name	`blitz3d-decomp`
Stars	9.2K
Forks	1K
Bundled files	7
License	MIT
Links	Skill source Repository

Markdown instructions
A SKILL.md file the model loads on demand, so it only costs tokens when a request actually matches.
Works with any LLM
AI skills are plain Markdown, not provider-specific code, so this works with GPT, Claude, Gemini, Grok, or a local model.
7 bundled files
Scripts, templates, and references the model can read while it works. Files are read-only and never executed.
Open source
Published by rehan-remade on GitHub. Read the source before you install it.

Installation

Install the Blitz3d Decomp AI skill in TypingMind to use it with any LLM, or drop it into another agent that reads SKILL.md.

Install in TypingMind

TypingMind installs a skill straight from its GitHub folder — it reads SKILL.md, bundles the resource files, and stores the result locally.

Open the app and go to Plugins → Skills.
Choose "Install from GitHub".
Paste the skill folder URL below and confirm.
https://github.com/rehan-remade/universal-modder/tree/main/.agents/skills/blitz3d-decomp
Enable the skill in any chat where you want it available.

Store

Installed

Skills

Add skills

Import one or more skills from a public GitHub folder or a local .skill or .zip archive, or SKILL.md file.

From GitHub URLFrom .skill, .zip, or SKILL.md

GitHub repo or folder

https://github.com/rehan-remade/universal-modder/tree/main/.agents/skills/blitz3d-decomp

Points to a single skill folder, or any folder that contains multiple skills. Public repos only.

CancelContinue

Plugins → Skills → Add skill → From GitHub URL, then paste the folder URL and press Continue.

Install in another agent

Any agent that reads the Agent Skills format can use this skill — copy the folder into that agent's skills directory.

Claude Code — .claude/skills

git clone --depth 1 https://github.com/rehan-remade/universal-modder.git /tmp/universal-modder
mkdir -p .claude/skills
cp -r /tmp/universal-modder/.agents/skills/blitz3d-decomp .claude/skills/blitz3d-decomp

Restart Claude Code after copying so it picks up the new skill.

Use it in TypingMind

Enable Blitz3d Decomp in any TypingMind chat and the model takes it from there. Its name and description sit in the system prompt, and the moment a request matches, the model loads the full instructions itself — you never invoke it by hand, and it costs no tokens until it is actually used.

The model loads Blitz3d Decomp on its own as soon as a request matches it.

Works with any AI model

AI skills are plain Markdown instructions rather than provider-specific code, so Blitz3d Decomp is not tied to the model it was written for. Install it once in TypingMind and use it with GPT-5, Claude, Gemini, Grok, DeepSeek, Mistral, Llama, or a local model you run yourself — all on your own API keys.

Loaded only when it is needed
The system prompt carries just the name and description. The instructions are fetched on the first matching request, so an idle skill costs nothing.
Switch models mid-chat
Because the skill is instructions rather than code, changing model does not break it — the next model reads the same SKILL.md.

Skill instructions

This is the SKILL.md content the model loads. Read it before installing — a skill is instructions your model will follow.

Blitz3D decompile and port

Blitz3D games ship as one exe: the runtime in .text and the compiled game in a resource module that the runtime links at load. Ghidra on the exe shows only the runtime. The route that works: B3DDecomp disassembles the module and decompiles it to Blitz source. Then the source is the spec for the port, and the original game stays the oracle.

Keep every disassembly and decompile outside any repo (convention: ~/<game>-decomp/), and never publish them; the scripts here are fine to keep. Leave proprietary DLLs that forbid decompiling alone: their export names in the exe are enough. Journal in the mod's MODLOG.md.

Read the source when there is one: SCP: Containment Breach (Regalis11/scpcb) and its Ultimate Edition Reborn fork (Jabka666/scpcb-ue-my) are open source under CC BY-SA 3.0.

What a port may use. A port that re-expresses a game's logic, or converts its models, keyframes, textures or sounds, redistributes that game once it is published or uploaded (to Roblox too). Port only what the user has the rights to: their own game, or an openly licensed one on its terms (SCP: Containment Breach: credit it and keep the port under CC BY-SA 3.0, and check each asset's credits, since fan games mix licences). Anything else stays a private study: nothing from it is uploaded or published.

1. Tools

B3DDecomp (juanjp600/B3DDecomp, C#, GPL-3): clone outside the repo, then dotnet build Blitz3DDecomp.sln -c Release. It needs a .NET 8 SDK; a user-local one installs without admin (dotnet-install.ps1 -Channel 8.0 -InstallDir <dir>). Run with DOTNET_ROLL_FORWARD=Major and bin/Release/net8.0 on PATH: the decompiler starts Blitz3DDisasm by name.
If one function aborts the whole run, apply references/b3ddecomp-skip-failures.patch (git apply; made on commit 2b3148b): the decompiler then skips a function it can't finish, with a step5 failed line, instead of stopping.

Done when Blitz3DDecomp.exe and Blitz3DDisasm.exe build.

2. Disassemble and decompile

Blitz3DDecomp.exe <copy of game.exe> writes <game>_disasm/ (Code/ per function, Type/, Strings.txt, BuiltIn/, Libs/, BuiltInSymbols.txt), then decompiles it to <game>_decomp/. Games built from SCP: Containment Breach's code need the game's fmod.decls as a second argument (B3DDecomp's README: the shipped decls drop a parameter from FSOUND_Stream_Open).

When it still aborts, the exception names the construct. Never make a type setter silently ignore writes to get past one: the type propagation then loops forever with no output.

Protected builds: stop. Some builds are protected against this step: a modified compiler and runtime hash every function, type and builtin name (B3DDecomp stops with Unrecognized function: @_builtIn_f<garbled>; SCP: Containment Breach 2's client is built this way), or the module is encrypted. Those are protections the developer added against decompiling. Don't reverse them: tell the user and stop (skills/mod-any-game/references/safety.md). Current B3DDecomp undoes one of them by itself, without saying so: an XOR on a .b3dmod section. List the exe's sections first (objdump -h, or any PE viewer) and stop if it has one.

Done when <game>_decomp/ holds Main.bb, Functions/, Types/ and Decls/ and the run prints at most a handful of step5 failed lines.

3. Find the system

Strings first: an asset path or sound the system loads (grep -l StringConstant_<n> Code/*).
Data-driven templates: the init function stores constants into a template per item. If the game has an addon/JSON loader, it names every field.

Done when every number the port will use is traced to the line that sets it and the line that reads it.

4. Port

Read references/blitz-runtime.md before writing port code: Blitz3D's clock, Animate, CurveValue, Euler angles, Rnd and entity calls behave in ways a straight transcription gets wrong. For animated .b3d models (viewmodels, rigs, keyframes) into Roblox, follow references/b3d-to-roblox.md; its scripts are in scripts/roblox/.

Port step for step: same order, same constants, same tick. Mark every deviation in a comment with the reason. The rights rule above covers the code as much as the models.

5. Verify against the oracle

Measure the port against the decompiled numbers in the engine, not by eye: rates (shots per second at the fixed tick), durations (frames / speed / ticks per second), aim (the sight's dot on the screen centre), ammo on the server. Record each check and its result in the journal.

Done when every ported behaviour has a measured number next to the decompiled one.

Bundled files

The model reads these on demand while the skill is loaded. They are exposed as readable files and are never executed.

Frequently asked questions

What does the Blitz3d Decomp AI skill do?

Why use Blitz3d Decomp on TypingMind?

Because you install it once and use it with any model. Blitz3d Decomp is plain Markdown rather than provider-specific code, so the same skill runs on GPT-5, Claude, Gemini, Grok, or a local model — and you can switch model mid-chat without it breaking. TypingMind runs on your own API keys, so you pay providers directly instead of a per-seat subscription, and your skills and chats stay in your own storage.

How do I install Blitz3d Decomp in TypingMind?

Open Plugins → Skills → Install from GitHub in TypingMind and paste https://github.com/rehan-remade/universal-modder/tree/main/.agents/skills/blitz3d-decomp. TypingMind reads its SKILL.md and bundles its files and installs it as a skill you can enable per chat.

Which AI models can use Blitz3d Decomp?

Any model you connect in TypingMind. AI skills are plain Markdown instructions rather than provider-specific code, so GPT, Claude, Gemini, Grok, and local models can all load this skill when a request matches it.

How many AI models can I use with Blitz3d Decomp?

As many as you like. As long as a model supports skills, you can use Blitz3d Decomp with it — GPT, Claude, Gemini, Grok, DeepSeek, Mistral, Llama and more — all on TypingMind with your own API keys.

Is the Blitz3d Decomp AI skill free?

Yes. It is published on GitHub by rehan-remade under the MIT license. You only pay your own AI provider for the tokens you use.

What are AI skills?

An AI skill is a reusable instruction bundle that teaches an AI model how to do one specific task. It follows the open Agent Skills format: a SKILL.md file with a name and description, plus any scripts, templates or reference files the model may need. The model reads the instructions only when your request matches the skill, so an installed skill costs nothing until it is used.

How are AI skills different from plugins or MCP servers?

A plugin or MCP server gives a model new tools to call — code that runs somewhere and returns a result. An AI skill gives the model knowledge and process instead: how to approach a task, which steps to follow, what good output looks like. Skills are plain Markdown, so they need no server, no API key and no runtime, and they work with any model.

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Overview

Installation

Install in TypingMind

Install in another agent

Use it in TypingMind

Works with any AI model

Skill instructions

Blitz3D decompile and port

1. Tools

2. Disassemble and decompile

3. Find the system

4. Port

5. Verify against the oracle

Bundled files

Frequently asked questions

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