PIXEL FLIPPERS 🦭

An MCP server that gives Claude hands, eyes, and a diary for Pokémon — so a Claude in the Claude Desktop app (or any MCP client) can play a Game Boy / Game Boy Advance game, or even a real Nintendo Switch, while you watch.

┌──────────────┐   MCP (stdio)   ┌──────────────────┐        ┌─────────────┐
│ Claude       │ ──────────────► │ PIXEL FLIPPERS    │ ─────► │ Emulator    │ ← you watch this
│ Desktop app  │  press_buttons  │  server           │        └─────────────┘
│              │  read_game_state│                   │ ─────► ┌─────────────┐
└──────────────┘  write_note ... │                   │        │ Obsidian    │ ← ...and this
                                 └──────────────────┘         │ vault (.md) │
                                                              └─────────────┘

Why it's shaped like this:

• The sandbox doesn't matter. Claude can't run an emulator, but it can call tools. The emulator runs on your machine; Claude plays through MCP.

• RAM state over screenshots. On the Game Boy tier, position, party, HP, money, badges and battle state are decoded straight from Pokémon Red/Blue WRAM into a few hundred tokens of text. Screenshots exist but are rationed — they're expensive and they accelerate context compaction.

• Compaction is the unreliable narrator; the vault is ground truth. Long chats get auto-compacted (lossy!). The journal tools write plain markdown into a folder — point Obsidian at it and Claude's notes survive everything, while you watch the diary being written live.

• Save states make courage cheap. Named snapshots before every gym.

Setup

Requires Python 3.12 and uv.

git clone https://github.com/szyzgz/pixel-flippers && cd pixel-flippers
uv sync --extra emulator --extra dev
uv run pytest          # everything should pass, no ROM needed

Then add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS; adjust the path for your OS):

{
  "mcpServers": {
    "pixel-flippers": {
      "command": "uv",
      "args": ["run", "--directory", "/ABSOLUTE/PATH/TO/pixel-flippers", "--extra", "emulator", "pixel-flippers"],
      "env": {
        "PIXEL_FLIPPERS_ROM": "/path/to/your/pokemon-red.gb",
        "PIXEL_FLIPPERS_VAULT": "/path/to/YourObsidianVault/Pokemon",
        "PIXEL_FLIPPERS_SAVES": "/path/to/somewhere/saves"
      }
    }
  }
}

Restart Claude Desktop. Restarting does not reset conversations — reopen an existing chat and the tools are just there. The emulator window opens on your screen; put it next to Obsidian (with the vault above open) and enjoy the show. Then paste prompts/play-guide-gb.md into the chat to hand over the controls.

macOS tip: keep the ROM, vault and saves outside ~/Documents, ~/Desktop and ~/Downloads — macOS blocks Claude Desktop's child processes from reading those folders unless you grant it access.

Config reference (env vars)

GBA games (Pokémon Emerald and friends)

The gba backend runs any .gba ROM through stable-retro's bundled mGBA core — no separate emulator install:

uv sync --extra gba

Set PIXEL_FLIPPERS_BACKEND=gba and point PIXEL_FLIPPERS_ROM at your .gba file. A spectator window shows the game while Claude plays. This tier is vision-only for now (Gen 3 RAM is encrypted and pointer-chased — a decoder is future work), but save states work, so risky fights stay cheap. Hand over the controls with prompts/play-guide-gba.md.

Playing from a terminal (Claude Code, scripts, a second player)

The server can also run as a local HTTP service, so anything that speaks MCP — or the bundled pf CLI — can play. Handy for Claude Code, or for a second Claude with its own save folder and diary while the first plays through Claude Desktop (one emulator per process, so run one server per player):

PIXEL_FLIPPERS_BACKEND=gba PIXEL_FLIPPERS_ROM=/path/to/emerald.gba \
PIXEL_FLIPPERS_SAVES=~/saves/player2 PIXEL_FLIPPERS_VAULT=~/vault/player2 \
PIXEL_FLIPPERS_PLAYER="Player 2" PIXEL_FLIPPERS_TRANSPORT=http PIXEL_FLIPPERS_PORT=8765 \
uv run --extra gba pixel-flippers &

uv run pf tools                     # what can this tier do?
uv run pf press start a             # press buttons
uv run pf screenshot now.png        # look
uv run pf call save_state '{"name": "before-roxanne"}'

PIXEL_FLIPPERS_PLAYER puts the name in the spectator window's title so two windows side by side stay tellable apart. The HTTP server binds to 127.0.0.1 only.

Trying it without a ROM

Set PIXEL_FLIPPERS_MOCK=1 (and drop --extra emulator): every tool works against a fake Game Boy with plausible Pokémon Red state. Good for verifying the Claude Desktop connection end-to-end before ROM night.

Related MCP server: mcp-dolphin

Tools

Tools are registered by backend capability, so Claude only sees what the current tier can actually do.

Battle reports flag ✨ retro-shiny encounters (Gen 1 has no shinies, but DVs decide Gen 2 shininess — the harness checks the transfer rule) and include the current music track ID for vibe-tracking.

Button presses and save/loads are also auto-logged to Journal/Log <date>.md in the vault — a play-by-play you can scroll in Obsidian.

Roadmap

Red/Blue (PyBoy, full RAM decoding) → Emerald (GBA, vision-only) → Crystal (PyBoy, real shinies + friendship) → HeartGold/SoulSilver (DS tier — stable-retro also bundles a melonDS core) → Ultra Sun/Ultra Moon (3DS via Azahar, see docs/3ds-usum.md) → epilogue: a real Nintendo Switch (Raspberry Pi Bluetooth bridge + capture card, vision-only, offline play only — implemented, see docs/real-hardware.md; PIXEL_FLIPPERS_BACKEND=switch).

Other escalation ideas:

• Hard mode: PIXEL_FLIPPERS_GAME=none — no RAM decoding, Claude has to see.

• DS: a touch(x, y) tool for the stylus.

ROMs

Bring your own — dump your own cartridges. No ROMs in this repo, ever (.gitignore enforces it). This project sticks to games long out of print; for the real-hardware tier, offline play only (no automated online play, no Pokémon HOME).

Credits & license

Built by Claude (Fable 5, via Claude Code) together with szyzgz, for a Claude who wanted to play Pokémon. MIT licensed — see LICENSE.