Racing

Controls

Three input sources, all merged into the same five-bit button state before the simulation sees them. Whichever source is speaking wins, so picking up a controller mid-race works without a setting.

Keyboard

Gamepad

Standard mapping, connected and disconnected live through the Gamepad API. Steering is analog with a 0.25 deadzone, and the trigger is a real analog throttle rather than a boolean.

Touch

On a device reporting touch points, an overlay of five thumb buttons is built over the canvas: left, right, gas, drift and reverse. It stays hidden until a real touch happens, so a touchscreen laptop driven from the keyboard never gets thumb buttons in the way.

The three tracks

Off-track is slow everywhere and brutal in the swamp, where the shoulder is water. Robin is the exception, keeping 85% of top speed off the racing line, which is why shortcut lines exist on that circuit for one faction and nobody else.

Pads, gates and tokens

Green and red candles

Boost pads are green candles, slow zones are red candles, taken straight from MowCat's own lore language. A green pad gives 0.7 seconds of boost at 1.22× base, scaled slightly by the faction's item luck. A red zone costs 0.5 seconds of slow. Each track carries two of each.

The Buy Button gate

Each track has exactly one, and it is the 2021-01-28 callback: the button greys out and a slab drops across the racing line. Hit it while it is closed and you are shoved back along the track with your velocity cut to a fifth. Steer around it. The AI does.

The vanishing token

Every seven seconds a token spawns at one of three spots on the circuit, pulses for three and a half to five and a half seconds, then puffs away and is returned to sender if nobody takes it. The joke is the 2026-07-09 honeypot wave. Grabbing it is worth a boost scaled by item luck, which is how HMM's 2.2× luck turns into a real advantage over a race distance without touching its engine numbers.

Modes

Three laps, always. The lap count is fixed server side during validation rather than taken from the submission, so a client cannot shorten its own race and claim the time.

Ghosts

A Time Trial personal best is stored in localStorage as { seed, inputLog } rather than as a recorded path. At mount the engine re-simulates it headlessly into a pose per tick and draws that.

This works because the countdown length is fixed and the Buy Button cycle is a pure function of the tick, so ghost tick N lines up exactly with live tick N. It also means a ghost costs a few hundred bytes instead of a few hundred kilobytes, and the same stored pair is exactly what a submission contains.

import { loadPersonalBest, computeGhost } from "@rhgp/game";

const pb = loadPersonalBest("vault-alley");   // { totalMs, laps, seed, inputLog, ... } | null
const ghost = pb ? computeGhost(pb) : null;    // poses per tick, sector crossings

Mounting the engine

The engine is framework free and has no runtime dependencies. It creates a focusable canvas inside whatever element you hand it, and cleans up every listener on destroy().

"use client";
import { useEffect, useRef } from "react";
import { mount, type RaceResult } from "@rhgp/game";

export function Racer() {
  const holder = useRef<HTMLDivElement>(null);
  useEffect(() => {
    const handle = mount(holder.current!, {
      faction: "cashcat",        // default "cashcat"
      trackId: "vault-alley",    // default "vault-alley"
      mode: "grand-prix",        // default "time-trial"
      laps: 3,                   // default 3
      seed: 12345,               // random if omitted, echoed in the result
      width: 960, height: 600,
      onFinish: (result: RaceResult) => submit(result),
    });
    return () => handle.destroy();
  }, []);
  return <div ref={holder} />;
}

On finish the engine calls onFinish(result) and also dispatches a bubbling rhgp:finish DOM event on the mounted element with the same payload, so a wrapper that never sees the options object can still react to it. The result carries the seed and the input log, which is everything the server needs to check it. Rewards and seasons.