Signal Overdrive

A Mode 7 racer in the spirit of F-Zero, set in the world of Crash The Stack and written in Sigil.

You're Zero, a data courier. Gibson owns every wire in the city, so the collective hides its messages inside songs, and couriers like you carry them by hand to pirate uplinks, where they go out over the air. Your cargo is the song, and its integrity is your energy meter. Boosting spends it, scraping a wall costs it, and the checksum lane wins it back. Deliver it clean and the whole city hears your song!

Play: signaloverdrive.net, free in your browser. The first build, 0.1, is coming soon: one track and one song, Carrier, wired through the whole race.

How to play

Each race is three laps against five rivals. They follow the racing line, bump you, and move across to block you, so you'll have to work for every place.

• Integrity is everything. The meter at the top is your cargo. Walls cost you, and boosting spends it. If it hits zero, the cargo is corrupt and the run is over.
• The checksum lane is the repair strip on the track. Drive through it and your integrity refills.
• Boost comes online on lap 2. It's fast, but every boost costs integrity, so pick your moments. Boost pads on the track give you a burst for free.
• ICE patches are the orange and red static on the road. Cross one and your steering scrambles for a second or so.
• Drift through the tight corners: hold the drift button and the machine slides instead of gripping.

The race follows the song's shape. Lap 1 is the verse, and your boost comes online with the chorus on lap 2. The final lap is the drop, and that's when Gibson finally traces you. You only hear the song's melody whole when you cross the uplink. From your second lap on, your best lap races alongside you as a ghost.

If your system asks for reduced motion, the game respects it: every effect keeps its meaning in color and in the HUD, but nothing tears, ripples or flickers. You can also turn it on with ?motion=reduce in the address.

Controls

	Keyboard	Gamepad
Steer	Left/Right or A/D	Left stick or d-pad
Accelerate	Up or W	A or right trigger
Brake	Down or S	B or left trigger
Boost (from lap 2)	Space	X
Drift (hold)	Shift or C	LB or RB
Start	Enter or Space	Start or A
Restart	R	Back

On a phone the machine accelerates by itself, and you pick one of three touch schemes with the button at the top left (it shows the current scheme's name):

• zones (the default): a thumb on the left half of the screen steers left, on the right half steers right, both thumbs brake, and the BOOST button boosts.
• drag: one finger anywhere steers by how far it slides sideways from where it landed. A second finger boosts as it lands and drifts while held.
• stick: a floating stick under your left thumb steers (pull down to brake). A thumb landing on the right half boosts, and drifts while held.

How it was made

I designed Signal Overdrive and I direct every part of how it's made. AI agents write the code, the music and the pixel art from my direction, and I play every build, listen to every sound, and decide what stays. No image generator was used: the machines, the track and the city are drawn by scripts an agent wrote. If the use of AI is a dealbreaker for you, I understand! The source and its commit history are all here, so you can see exactly how it was made.

Building and running

You'll need the Sigil toolchain version the repo pins (the sigil: line in package.sgl; sigil cli use picks it) and, for the native build, the C libraries that manifest.scm lists. scripts/dev runs a command inside that environment through Guix.

scripts/dev sigil deps install                the dependencies, from sigil.lock
scripts/dev sigil build                       the native dev build
scripts/dev ./build/dev/bin/signal-overdrive  run it
scripts/dev sigil build --config release      the native release build
scripts/dev sigil build --config web          the browser build, in build/web

To play the browser build, serve it locally:

node scripts/serve.mjs build/web 8080 --loopback

and open http://127.0.0.1:8080/. serve.mjs also sends the cross-origin isolation headers that give the game its best audio path. Opening index.html straight from disk won't work.

The tests are in test/. Run one file with scripts/dev sigil test --sgl test/test-handling.sgl (and likewise for test-race, test-track, test-fx and the rest).

Where things are

• src/signal/mode7/ is the Mode 7 camera and renderer: a fragment shader that projects the tiled track toward the horizon.
• src/signal/handling.sgl is one machine's handling, track.sgl the track probes and catalog, race.sgl the grid, laps, rivals and the finish, and scene.sgl the frame: the Mode 7 pass, the palette and dither pass, and the HUD.
• src/signal/music/ and music/ are the soundtrack. The songs are written for the motif synth engine, and docs/CONDUCTOR.md describes how the race and the song keep time.
• scripts/art/ holds the generators for every image in assets/signal/ (Node, no dependencies).
• tracks/ holds track authoring data. The authoring guide covers the map/song preview and gates. The prototype loop is retired; the oval remains a handling test while the new district tracks are authored.

Development tools

The game carries the tools I use to tune it. In the native build they're always on. In the browser build, add ?dev to the address to turn them on, so a player can't trip them by accident.

• Tab opens the tuning overlay (Up/Down pick a knob, Left/Right change it, 0 resets it). Every knob also takes a URL parameter of the same name, with or without ?dev, so ?grip=8.5 sets the grip from the address. signal-overdrive --knobs prints the full table.
• ?fps shows the frame rate, the frame's timings and the audio readout, with a graph of the last 180 frames, and works for anyone. F3 toggles it. While it's on, F4 prints the recent hitches to the console. F5 pauses the native build.
• With ?dev, the browser build also gets the effects panel (the EFFECTS button, or E): each effect's toggle and intensity, solo, and a button that fires each trigger. F2 and F6 to F10 do the same from the keyboard. docs/effects.html describes the effects.
• P switches the palette and / toggles the dither, in every build.
• Other parameters: ?track=oval (the handling test track), ?start (skip the title), ?card=0 (skip the card before it), ?mute, ?autopilot, and ?touch=zones|drag|stick.

Licenses

The code is GPL-3.0-or-later (LICENSE). The art, the music and the content are CC-BY-4.0 (assets/LICENSE), credit David Wilson / Flux Harmonic, except the reserved marks in assets/RESERVED.md: the name, the logo and the Flux Harmonic mark. The third-party notices, including the site's font, are in NOTICE.

Links

• signaloverdrive.net, the game's site
• github.com/FluxHarmonic/signal-overdrive, the source
• Flux Harmonic, which makes it, along with Crash The Stack, Harkfell and Phantom Burn