doom: DOOM in Claude Code

A Claude Code mod that plays DOOM in the side pane. The engine is doomgeneric. The game data is Freedoom, which /doom download fetches for you, or your own DOOM WAD.

Any terminal: quadrant cells	kitty / Ghostty: real pixels

These pictures are rendered from the game's own output: the left one simulates how a terminal draws the cells, the right one is the raw frame an Image shows.

Install

At the prompt of a Claude Code terminal session:

/plugin install doom --marketplace emirtuncer/doom-mod

Answer y to add the marketplace, then pick a scope (user scope is first; press Enter).

From a shell:

claude plugin install doom --marketplace emirtuncer/doom-mod

Game data

The repository holds no game data. Before the first game, pick one:

• Freedoom: type /doom download. It fetches Freedoom 0.13.0 (24 MB) with curl and unpacks it into ~/.claude/doom/ with tar (or unzip, or python3).
• Your own WAD: set DOOM_WAD to its path (for example doom1.wad or doom.wad) before starting Claude Code.

The mod looks for the WAD in three places, in this order:

1. DOOM_WAD;
2. the mod's own wad/freedoom1.wad;
3. ~/.claude/doom/.

Play

1. Type /doom. The game opens in the side pane, straight into the first level.
2. Click the line under the picture to give the game the keyboard; Esc takes it back.
3. Type /doom stop to quit.

Key	Action
W S / ↑ ↓	forward, back
A D / ← →	turn
Q E	strafe
Space / F	fire
R	use (doors, switches)
1–7	weapons
Tab	map
P	menu (Esc is the terminal's)
Enter	select

A terminal reports key presses but not releases, so a key counts as held while it repeats.

Picture quality. Two modes, picked by itself:

• Pixels, in kitty and Ghostty: the 320×200 frame drawn as a real image. WezTerm cannot: it draws no "placeholder" images, which Claude Code uses.
• Cells, everywhere else (Windows Terminal and xterm.js terminals included): each cell is a 2×2 quadrant glyph in two colours, up to 160 cells wide, which is DOOM's own width.

To pick a mode yourself, set DOOM_MODE=pixels or DOOM_MODE=cells before starting Claude Code (for example DOOM_MODE=cells if a terminal is taken for kitty but shows no picture).

In cells mode a wider pane and a smaller font give a sharper picture. /doom asks for a 162-column pane; drag the divider if your terminal keeps it narrower.

There is no sound.

How it works

• bin/<platform>/doom-claude is doomgeneric with a platform layer (engine/doomgeneric/doomgeneric_claude.c) that opens no window. It writes each frame to stdout, as cells (base64 of a Raster's cells) or, in pixels mode, as raw RGB in a few files used in turn.
• The mod (hooks/register.tsx) runs it with $.process.spawn and blits each frame into the pane: a Raster for cells (blitted in place), an Image for pixels (the pane redrawn with each new frame).
• A Client region (hooks/keys.tsx) catches key presses. The mod writes them to a small file, which the game reads every tick, since a spawned process takes its stdin once.

Builds: Windows x64, Linux x64 (static), macOS arm64 and x64. Tested so far: cells mode on Windows (Windows Terminal, WezTerm), and pixels mode on Linux in kitty (under WSL). The macOS builds have not been run yet.

Build the engine

sh engine/build.sh /path/to/zig

This needs zig 0.13, and builds every platform from any of them. engine/doomgeneric is doomgeneric at upstream commit e257a09, with doomgeneric_claude.c added.

License

GPL-2.0, as doomgeneric is (see LICENSE). Freedoom, fetched by /doom download, comes under its own BSD-style license. DOOM is a trademark of id Software; this project is not affiliated with id Software.