Cervix Command

A Missile Command–style game, reskinned as biology: instead of cities under a nuclear barrage, you are the reproductive tract defending six ova against an endless swarm of sperm. Your central mucus cannon (the cervix) sprays a rapid-fire stream of cervical mucus; the supply is endless, but globs arc and slow with distance, so you still have to lead your targets.

Rendered in WebGL (Three.js) with bloom for a warm, glowing, fleshy interior, while the gameplay stays a flat 2D plane viewed nearly head-on.

Play

▶ Play it in your browser — hosted free on GitHub Pages (auto-deploys from main). To run locally:

python3 serve.py 8011      # or: bun run serve
# then open http://localhost:8011

serve.py is a tiny static server that sends no-cache headers (so edits always show up). Or use the ciws config in .claude/launch.json with the preview tooling.

Tests

Game logic has a unit suite run with Bun (no dependencies):

bun test          # or: bun run test

It covers utils, physics, the entities (ballistics, drag, clump split, antibody boost/coast/energy), the weapon systems, the high-score table, the save checkpoint, and the Game orchestration (waves, spawning/threat gating, collisions & HP, bounties, impacts and mutant air-bursts, enzyme bombers, the autonomous antibody gland and acid gland, the economy, the biolab, and win/lose conditions).

The simulation is headless-testable because the WebGL renderer is injected into Game rather than imported — see the architecture note below.

For hands-on testing there is also a hidden dev console: press ` (backquote) in any state. It offers god mode (ova & cervix invincible) and endless single-threat sandboxes (loop enzyme bombers, swarmer swarms, mutants, etc.) for observing sperm and autonomous-defense behaviour in isolation. Dev runs are marked with a DEV badge and never touch the high-score table.

Controls

Input	Action
Mouse move	Aim the mucus cannon — it fires on its own while sperm are inbound
Touch (mobile)	Drag on the aim pad below the field — an absolute aim mapping, so your thumb never covers the action (touching the field directly also aims)
P	Pause / resume
R	Restart
M	Mute / unmute
Space / click	Defend from the tutorial screen / restart after game over (with a saved run, Space continues it)

You aim; everything fires itself. The mucus cannon sprays wherever you point it (and holds fire when the field is clear), antibodies launch themselves at distant high-value swimmers, and the acid gland handles whatever gets close. A tutorial screen at the start covers all of this in-game.

Defenses

• Mucus cannon — a single central rapid-fire gland with an endless supply that sprays automatically while sperm are inbound; you steer the stream with the mouse and must lead targets. One glob kills a standard sperm. If a sperm ever reaches the cervix, you instantly lose — so anything heading for the centre is top priority.
• Antibodies (autonomous) — a cheap biolab purchase (the natural first buy) that fields homing antibodies with unlimited stock, gated by a synthesis cooldown (6s at the start; biolab upgrades buy it down to 1s); the gland comes back fully stocked each wave. It fires itself at the highest-value, most distant swimmer — it never engages cheap clutter (swarmers and acrosome bombs are the acid gland's and cannon's business, though a blast can still catch one), can't see cloaked ghost sperm, and won't shoot inside its minimum engagement distance. Antibodies launch straight up from the gland — guidance stays locked for the first ~100px of climb — then turn onto an intercept course — but coasting flight bleeds energy, hard turns scrub extra speed, and an antibody that drops below maneuvering speed breaks down: some intercepts genuinely run out of energy. If the target dies en route the antibody retasks onto the nearest valid swimmer (or breaks down), and it detonates with an area blast.
• Acid gland (biolab upgrade) — a fully autonomous pH beam emplacement left of the cervix with a trainable emitter head. It picks the lowest swarmer or normal-type sperm in range (it can't track the fast movers), physically slews onto it, and only then dissolves it over time. It can't depress below ~15° above the horizon, so wall-huggers slip under its arc. Output falls off with distance — full power up close, weaker out toward its maximum range, beyond which it can't latch at all. After each kill it rebuilds acid (~6s, upgradable to ~2s).

Economy & biolab

You earn ATP (separate from score) from several sources, shown as a breakdown on the wave-clear screen:

• Kill bounties, scaled by sperm type — standard/swarmer/acrosome 1, wriggler 2, sprinter/wall-hugger 3, clump/ghost/enzyme-bomber 4 (split clump children pay the standard rate), mutant 12.
• All-clear bonus for repelling every sperm that wave (nothing leaked).
• Ova saved — per surviving ovum.

Between waves the intermission becomes a biolab — click an item (or press its number), hover any row for a fuller explanation, then NEXT WAVE / Space to continue. Every ladder runs deep enough to soak late-game ATP:

Item	Effect
Antibody Gland / Synthesis	Field the auto-launcher (cheap!), then shorten its cooldown, 6s → 1s (multi-level)
Mucus Plug / Regrowth	Fit a plug on the cervix that absorbs one sperm, then buy down its regrowth (multi-level)
Acid Gland / Buildup	Buy the autonomous beam, then speed its buildup (multi-level)
Upgrade Spray Rate	Faster mucus cannon cycle rate (multi-level)
Twin Glands	One-time: a second nozzle spraying side-by-side (2× globs)

The Mucus Plug (a regular biolab item) fits over the cervix and intercepts one sperm on contact — the sperm bursts against the plug instead of the cervix — then fails with a burst and regrows (~10s, upgradable down to ~2.5s via Mucus Regrowth levels). Ova can't be plugged; the plug is how you survive a hit that would otherwise instantly end the run.

There are no ovum repairs — a lost ovum is gone for the run, taking its end-of-wave income with it.

Prices, amounts and earnings live in config.economy, config.shop, and config.shield.

Rules

• 6 wide ova cluster around a single central cervix — flanked, once bought, by the acid gland (left) and the antibody gland (right; the next antibody's tip pokes from the gland whenever a launch is ready). Most sperm rain from the top; wall-huggers, swarmer swarms and enzyme bombers sweep in from the edges.
• The cannon tracks the mouse. Globs disperse in a small cone, so closer, well-led shots land more reliably. One hit destroys a standard sperm.
• A sperm reaching an ovum blasts everything within its radius — a hit anywhere on an ovum's footprint counts, not just dead centre. Lose all ova, or take a single sperm on the central cervix, and it's game over — unless a mucus plug is up to absorb it (see the biolab).
• Sperm are programmed against ova that are alive or ruptured earlier this same wave (their salvo was targeted before the ovum dropped); from the next wave on, known wreckage draws no fire. About a third of all swimmers miss into the gaps regardless.
• Clearing a wave awards bonuses for surviving ova, and the antibody gland and acid gland come back fully charged.
• Game over shows a local high-score table (top 10, stored in localStorage) with your run highlighted.
• Progress is checkpointed in localStorage whenever a wave is cleared — before any biolab spending, so a closed tab isn't a lost run: the menu offers CONTINUE (resume at the biolab before the saved wave — upgrades, ATP and wreckage intact, shopping never skipped) or NEW CYCLE (forfeits the save). A reload after shopping simply refunds those purchases to re-pick; the next wave clear banks them. Game over deletes the checkpoint — defeat is final. Dev-console runs (sandbox / god mode) never touch it.

Sperm

Threat	Appears	Behaviour
Sperm (pale cream)	wave 1+	Straight dive toward an ovum; 1 hit
Swarmer swarm (gray, squat)	wave 2+	Five low gliders from one screen edge (counts as one wave slot), each with its own target; 1 hit each
Wriggler (purple)	wave 2+	Weaves on an irregular path; 1 hit
Clump (green, large)	wave 3+	Armoured (3 hits); splits into single sperm at altitude
Wall-hugger (gold)	wave 3+	Enters from a screen edge at low altitude, pops up, then dives; 2 hits
Enzyme bomber (bronze)	wave 4+	Crosses fast at mid altitude dropping 2–3 acrosome bombs (1 hit each — yes, you can dissolve acrosome bombs in flight). The bomber flies defensively: it weaves whenever an antibody is hunting it or its own decoy, ejects bursts of decoy proteins that can seduce the antibody, pulls high-g S-breaks when the antibody closes, and weaves out of incoming mucus streams — all under honest energy physics (total speed stays near cruise; a pull pitches the flight path, it doesn't add free velocity). Forcing a bomber to jink aborts its run for good — suppression is a mission kill. About 40% survive a full defensive engagement. Killing it pays 4 but it exits without leaking if you let it go; 3 hits
Sprinter (orange dart)	wave 4+	Very fast and barely slows in the dense fluid; 1 hit but hard to track
Ghost sperm (pale, ghostly)	wave 6+	Flies the wall-hugger profile cloaked — invisible, silent, no lock-on, no acid — until its pop-up; a blind mucus sweep can still clip it; 2 hits
Mutant (crimson, huge)	wave 5+	Announced by a klaxon and a "Mutant swimmer detected" voice; never the first or last threat of a wave, and the per-wave cap keeps climbing in later waves (one at wave 5, two at 8, three at 11...). Full speed and heavily armoured (30 hits — a single antibody barely dents it). Targets inner ova and bursts over them, leveling the target and both neighbours — including the cervix if it's next door — then a bloom of cytoplasm climbs

A non-killing hit on the armoured clump flashes it white with a wet thud — chip it down with the cannon, or pop the whole clump with one antibody before it splits. Sperm speed is constant across waves (~190 px/s base); difficulty ramps via sperm count, spawn cadence, and the mix, not speed.

Per-type hit points live in config.missile.hp and are fully tunable.

Physics

A simple shared atmosphere (physics.js) governs everything that moves. The fluid is thin up high and dense near the wall (density decays exponentially with altitude), and quadratic drag scales with that density and with speed:

• Mucus globs feel gravity and drag — they slow and arc, so long shots need lead (the cannon is genuinely close-in). A glob burns out once it slows below a threshold speed: a straight-up burst just reaches the top of the field and dies near apogee, while a flat shot keeps flying its whole arc — still lethal on the way down.
• Sperm feel drag only (no gravity, so they still track their target) — they decelerate as they sink into denser fluid, giving you more time to engage them low.
• Antibodies fly a real two-phase profile: a powered boost (with a propulsion surge) that accelerates them to top speed, then an unpowered coast where gravity and drag bleed off energy while they keep steering. Their turn rate and acceleration are limited, so they reliably kill slow/ straight sperm but can overshoot and miss fast ones — late-game sprinters in particular will sometimes outrun them.

Tunables live in config.physics (gravity, scale height, per-projectile drag). The play field (config.world) is deliberately large so there's plenty of room.

Architecture

Vanilla JS + Canvas/WebGL, no build step. Three.js is vendored locally under vendor/three/ (resolved via the import map in index.html), so the game runs fully offline.

File	Responsibility
index.html / style.css	Import map + layered canvases (WebGL scene, 2D HUD)
js/config.js	All tunable values — balance the game here
js/strings.js	All user-facing text — menus, HUD, biolab copy
js/utils.js	Math helpers (clamp, rand, distance, array culling)
js/physics.js	Altitude-based density model + quadratic drag helper
js/entities.js	City, Turret, Bullet, EnemyMissile, Interceptor, Flare, Particle (data + update, no draw)
js/weapons.js	CIWSWeapon, InterceptorWeapon, LaserWeapon — stats, upgrades, fire logic
js/scores.js	Local high-score table (localStorage, injectable for tests)
js/save.js	Run checkpoint save slot (localStorage, injectable for tests)
js/audio.js	Procedural Web Audio SFX + speech announcements (singleton sfx)
js/renderer3d.js	Renderer: Three.js scene, bloom, GPU buffers, projection
js/game.js	Game: state machine, waves, input, simulation, 2D HUD
js/main.js	Canvas wiring + rAF loop + frame-rate quality governor
vendor/three/	Pinned Three.js r160 core + postprocessing addons
serve.py	No-cache static dev server
tests/	bun test suite + setup/helpers

The internal code keeps its original military identifiers (turret, missile, interceptor, laser, nuke, mirv…); only the user-facing text and palette are reskinned, so the engine and its test suite are untouched by the theme.

Dependency injection: main.js constructs the WebGL Renderer and passes it into new Game(hudCanvas, renderer). Game never imports the renderer (or Three.js), so the whole simulation loads and runs headlessly under bun test with a stub renderer. Audio is likewise inert until a user gesture calls sfx.unlock(), so it needs no stubbing in tests.

Separation of concerns: the simulation runs in a fixed virtual resolution (config.world, default 1400×1350) so balance — distances, speeds, gland spacing — never depends on the window size. The camera frames that field edge-to-edge vertically at any window aspect; on wide monitors the HUD docks into the spare columns beside the field (and collapses into corner overlays on narrow ones). renderer3d.js maps sim space to 3D world space, draws everything as emissive neon with an UnrealBloom pass, and exposes screenToWorld / worldToScreen so input and the HUD overlay stay aligned with the tilted camera. The HUD, menus and biolab are drawn in screen space on a 2D canvas. Entities carry no draw code — the renderer reads their fields.

License

MIT (see LICENSE). Three.js is vendored under vendor/three/ and carries its own MIT license.

Roadmap

This is the foundation for a broader biological-defense game. Natural next steps:

• More defense systems on the weapons.js abstraction (e.g. spermicide bursts, long-range immune patrols) and more biolab upgrades.
• More sperm variety: saturation salvos, decoys, chemical jamming.
• Deeper economy: persistent upgrades across runs, ovum armour, etc.
• A music bed and an online leaderboard.