MIMEcroft.sh

a first-person 3D maze treasure hunt rendered over WebGL — written entirely in bash

▶ Play MIMEcroft.sh in the browser shell

opens the shell at www/index.html and auto-starts the game via the allow-listed ?demo=MIMEcroft.sh parameter (see SECURITY.md) — the game boots as the MIMEcroft command (the script is bin/MIMEcroft.sh). You can also just open the shell and type MIMEcroft.sh (or mimecroft.sh).

What it is

You are the shell command Mime Croft on the hunt for hidden treasures inside an ancient yet sacred filesystem on Phobos. The maze around you is made of data blocks — coloured chunks of file content. Somewhere in the depths lie hidden treasures: the Great Operating Systems (GNU Hurd, Linux, FreeBSD, NetBSD, OpenBSD, Plan 9, Minix, Solaris, macOS Darwin, Unix) preserved as artifacts. But the filesystem is infested with evil MIMEs — misbehaving content types (image/jpeg, image/png, application/octet-stream, text/plain) that hunt you through the corridors.

Your gun fires a single ray of pure type-checking. Shooting a block mines through the data; shooting a MIME sanitises it. Walk into a hidden treasure to recover it — shooting one shatters the artifact and costs you an archaeology-licence strike (three strikes and the Board revokes it).

WASD move · ←/→ turn · SPACE shoot · Q quit · ESC settings

The settings menu tweaks the camera shift, texture size/seed, CRT & corruption effects, the minimap, mime speed and the sound mode (notes oscillators or bash — sample-accurate generators).

Why it's interesting

The whole game is one bash script (bin/MIMEcroft.sh, ~3,900 lines) that runs in the browser via the shell's bash→JS transpiler — no build step, no WebGL API calls in the game itself.
The GPU shaders are written in bash too and compiled to GLSL ES 1.00 at startup by the sh→GLSL backend (see WRITING_GPU_SHADERS_IN_BASH.md).
The block textures and sound effects are synthesised by bash: pseudorandom value-noise texture generators and sample-accurate DSP sound generators, all deterministic per seed.
Every browser capability is a file: the game renders by writing cubes to /dev/webgl and plays by writing samples to /dev/audio — the Plan 9-style filesystem-as-API metaphor (see bash-game-vision.md and mimecroft-proposal.md).

The implementation — the .sh files

bin/MIMEcroft.sh ~3,900 lines

The game itself — the MIMEcroft command (the lowercase bin/mimecroft.sh alias still works). One script does everything:

world generation — a seeded drunkard's walk carves the corridors over a 16×16×3 block grid; an indestructible obsidian ring borders the maze; coloured gem blocks and grass patches are scattered deterministically
rendering — a painter's-algorithm scan (far-to-near along the facing axis) writes every visible cube to /dev/webgl/blocks in one batched payload per frame; a continuous frustum culls off-screen cells; floor/ceiling planes follow the camera
gameplay — movement/turn glides, a ray-cast shot with per-material hardness and damage (blocks crack, then break), hidden treasures claimed by walking in, and MIME entities that hunt or flee
HUD — a canvas radar/minimap, score/hp/licence/fps digits in a 3×5 pixel font, floating treasure-name labels, a view-model gun with muzzle flash, and the settings menu
assets — loads the generated textures, treasure labels and MIME banners through /dev/webgl/texture, and plays sounds through /dev/audio

examples/mimecroft-vertex.sh ~50 lines

The vertex shader authored in bash. Object→world transform, the camera-relative delta, the yaw rotation (cos/sin via bc), and the fake perspective (gl_Position = (rel×0.45, w²/64, w)). Compiled at startup by sh2glsl --vertex into GLSL ES 1.00; the compiled reference is examples/mimecroft-vertex.glsl.

examples/mimecroft-frag.sh ~68 lines

The fragment shader authored in bash: per-pixel block-texture tint, the crack-overlay blend on damaged blocks, and the optional CRT scanlines / corruption streaks / vignette. Every intermediate is bounded to fit precision mediump int. Compiled by sh2glsl; the compiled reference is examples/mimecroft-frag.glsl.

examples/textures/ 17 generators

Pseudorandom, seamlessly tileable block textures, generated by bash (seeded LCG + value noise, no floats, no $RANDOM), deterministic per seed. README. The core texture-lib.sh is inlined into each generator so they run identically under host bash, the real-bash wasm, and the transpiled shell:

stone · sandstone · dirt · grass · leaves · wood · brick · water · obsidian — the block walls/floor
chest — the treasure-artifact side (wood + iron struts + latch)
crack — the transparent RGBA damage overlay on mined blocks
jpeg · png · octet · text — the MIME entity icons (a tiny DCT-grid photo, a transparency checkerboard, a hex dump, a text page)
read-texture.sh · make-textures.sh — TSV reader + one-shot PPM→PNG→contact-sheet batch

examples/sounds/ 12 synthesizers

Every game sound as a list of signed 16-bit PCM samples at 22050 Hz, synthesised in bash (sine-table waveforms, envelopes, seeded noise) and played through /dev/audio/samples in the game's bash sound mode. README:

hit (material-dependent tick) · break · thud · shoot · kill · damage
treasure (recovery fanfare) · shatter · walk · mime
make-sounds.sh (batch .wav/.tsv) · audition-sounds.sh (A/B audition)

How it runs

The page's bash→JS transpiler turns MIMEcroft.sh into JavaScript against the sh2 runtime; the /dev/webgl device (src/fs/webgldev.js) provides the WebGL context as files (shader/, buffer/, uniform/, call, blocks), and /dev/audio plays the notes or sample lists. The same script runs headless in the Node CLI (a null WebGL device), which is how the game is regression-tested.

MIMEcroft lives in the j.cmd repo — the game, its shaders, textures and sounds, all written in bash.