Mewgenics Cat Bridge

Let Claude see and manage your cats in a running game of Mewgenics.

A small mod DLL reads the game's memory live and a Python MCP server turns it into tools an AI assistant can use: your cats' stats, abilities, mutations and family trees, the rooms of your house, and advice on breeding, strays and adventures. It can also edit cats (stats, passives, body parts).

Русская версия

Unofficial fan project. Not affiliated with or endorsed by Edmund McMillen, Tyler Glaiel or the publishers of Mewgenics.

What you can ask

• "Which two cats should I breed for strength and constitution, without inbreeding?"

• "Plan three generations of breeding towards all 7s."

• "Is today's stray worth adopting?"

• "Which cats aren't needed for breeding? Build me an adventure party and pick their collars."

• "How should I set up the Floor1_Small room for breeding?"

• "Show me Sosakus's family tree. Is Dushenka inbred?"

• "Give Bukhoslav the Toad Style passive." / "Remove Pox from Grimurir."

Related MCP server: ck3-strategy-advisor

Features

Requirements

• Windows, Mewgenics from Steam — game version 1.1.21239 (see Game updates)

• Python 3.10+, 64-bit, with "Add python.exe to PATH" ticked

• An MCP client: Claude Desktop or Claude Code

Installation

1. Download mewgenics-cat-bridge-vX.Y.Z.zip from Releases and unzip it anywhere, e.g. C:\mewgenics-cat-bridge.

2. Install the Python packages — open a terminal in that folder and run:

   pip install -r requirements.txt

3. Connect it to Claude.

   Claude Desktop — Settings → Developer → Edit Config, and add (use your own path, with double backslashes):

   {
     "mcpServers": {
       "mewgenics": {
         "command": "python",
         "args": ["C:\\mewgenics-cat-bridge\\mcp_server\\server.py"]
       }
     }
   }

   Restart Claude Desktop.

   Claude Code:

   claude mcp add mewgenics -- python C:\mewgenics-cat-bridge\mcp_server\server.py

Every play session

1. Start Mewgenics and load your save (be in the house).

2. Double-click inject.bat. It should say injected ... into pid ....

3. Talk to Claude.

The mod stays loaded until you close the game; run inject.bat again after each game start. eject.bat unloads it without closing the game.

The game folder is found automatically through Steam. If yours isn't found, set the environment variable MEWGENICS_DIR to the folder that contains Mewgenics.exe.

Safety

• Reading never changes anything. Edits (set_* tools) change the running game's memory, and the game saves them like any other change. Claude should ask before editing — and you can always ask it to undo, since every edit reports the previous value.

• Save before experimenting. The game also keeps its own backups in %APPDATA%\Glaiel Games\Mewgenics\<id>\saves\backups.

• The mod checks the game's exact version (SHA-256 of Mewgenics.exe) and stays inactive on any other version instead of guessing.

Game updates

This release is built for Mewgenics 1.1.21239. After a game update the mod stays inactive (tools answer "timed out" / "could not connect") until a new release adds the new version. If you build from source you can usually update it yourself in a minute — see docs/DEVELOPMENT.md.

Troubleshooting

How it works

Mewgenics.exe ── cat_bridge.dll (injected) ── named pipe ── mcp_server (Python) ── Claude
                 reads/writes game memory                   + game data from resources.gpak

The DLL hooks the game's per-frame update and answers one command per frame on the game thread, so it never touches memory while the game is changing it. Everything it knows was reverse-engineered and checked against the game's UI, its data files and its save format; docs/DEVELOPMENT.md lists what is verified and what is still a hypothesis. In short:

• Verified in-game: displayed stat formula, heritable (base) stats, body-part mutations and how they stack, room Comfort with crowding penalty, pedigree and inbreeding coefficient (matches the game on every cat), who lives in the house vs. the stray, stat / passive / body-part editing.

• Measured on a real save: ability inheritance (≈32% a parent's innate ability, ≈2% a learned one, ≈66% random).

• Read from the game's code: the cat info labels (libido, aggression, inbreeding, orientation; checked in-game) and the mating formula (libido, orientation, partner's charisma, room Comfort, fertility).

• Checked on real births (17 in-game nights, 60 kittens, logged with tools/birth_logger.py): litter size from fertility matches the game's formula; a pair alone in a room breeds about as often as the formula says; which parent a kitten's stat comes from is about a coin flip (55% the better one) at any Stimulation from 0 to 200 — the popular "Stimulation 32 / 95 / 196" tiers did not hold up.

• Still open: how a cat picks its partner for the night in a shared room, so mating chances there are an upper bound.

Building from source

Needs Visual Studio 2022+ (or Build Tools) with "Desktop development with C++".

git clone https://github.com/z3ndroot/mewgenics-cat-bridge
cd mewgenics-cat-bridge
pip install -r requirements.txt
powershell -ExecutionPolicy Bypass -File mod\build.ps1      # -> bin\cat_bridge.dll

Add -Console to get a log window next to the game. See docs/DEVELOPMENT.md for the architecture, the pipe protocol and how to reverse-engineer new structures.

Credits

• The mod is built on mewgenics_randomize_item_picks by polymeric (MIT) — the base DLL framework, signature scanning and the reconstructed game structures.

• Libraries: Detours, LibTomCrypt, Mewjector, SDL headers, pefile — see mod/ATTRIBUTION.md.

• Breeding-model hypotheses: jph6366/mewgenics-mcp and the Steam community guide by RedettFZ.

License

MIT. Parts of mod/ are © polymeric under MIT; vendored libraries keep their own licenses.