Kart racer template (TORQUEBAY)

Net Forge, the open-source multiplayer browser game engine built for AI coding agents, is published on npm under @netforge with source at github.com/netnetdev/net-forge.

TORQUEBAY is a complete online kart racer for up to eight players: hold the throttle, drift through bends to charge a mini-turbo, hit boost pads, collect coins that raise your top speed and keep off the grass. A round is one race of a few laps on one of three harbour circuits, and seat bots fill the grid so one person alone still has a field.

npm create netforge@latest my-game -- --template racer --yes
cd my-game
npm run play

--template kart works too. Keys: W or Up to accelerate, S or Down to brake, A D or arrows to steer, hold Space or Shift through a bend to drift and release for the boost, R or Enter to ready the next race.

#What you get

Measured on an Apple M2 Pro, Node 22: four playtest drivers plus seat bots over four minutes (14,400 ticks at 60 Hz) ran two full races, every driver finished both, nobody hit a wall hard, and the server tick stayed under 0.09 ms at p99.

#1. Add a circuit

points is the closed centreline in driving order, in metres on the ground plane; a smooth curve runs through them. boosts and coins are [lap fraction 0..1, lateral -1..1].

import { game } from "@netforge/engine";

const coinRow = (f: number, lateral: number, n: number, gap = 0.006): [number, number][] =>
  Array.from({ length: n }, (_, i) => [f + i * gap, lateral]);

export default game({
  template: "racer",
  style: "lowpoly",
  tickRate: 60,
  places: { harbour: { chunks: "places/harbour", spawn: [0, 0, 0] } },
  players: { prefab: "style.lowpoly.kart_a", max: 8, bots: 6 },
  round: { seconds: 240 },
  tracks: [
    {
      name: "Pier Sprint",
      laps: 3,
      width: 14,
      points: [[0, 0], [90, 0], [150, 15], [175, 65], [150, 120], [90, 135], [50, 175], [-20, 190], [-85, 160], [-110, 100], [-90, 35]],
      boosts: [[0.12, 0], [0.47, -0.4], [0.78, 0.4]],
      coins: [...coinRow(0.04, 0.5, 5), ...coinRow(0.3, -0.5, 5)],
    },
  ],
});

A track has 4 to 64 control points at least 6 m apart and is at least 200 m round. As a rule of thumb, 500 to 900 m a lap at 14 m wide runs 25 to 40 s a lap, a hairpin needs about 25 m of radius, and boosts belong on the exits of bends.

#2. Tune the handling

Add kart: { topSpeed: 30, turn: 2.6, grip: 10, driftGrip: 1.5 } to game({...}). The ranges are topSpeed 10 to 45 m/s (default 26), accel 8 to 80, turn 1 to 4, grip 3 to 20, driftGrip 0.5 to 6, grass 0.2 to 1 and boostSpeed 1 to 1.8.

#3. Reward a clean race

import { earn, system } from "@netforge/engine";

system("clean_line", ({ on, emit }) => {
  const scrapes = new Map<number, number>();
  on("kart.bumped", (ids) => {
    for (const id of ids) scrapes.set(id, (scrapes.get(id) ?? 0) + 1);
  });
  on("player.finished", (ids) => {
    const clean = ids.filter((id) => (scrapes.get(id) ?? 0) === 0);
    if (clean.length > 0) emit("race.clean", clean);
  });
  on("run.started", (ids) => {
    for (const id of ids) scrapes.delete(id);
  });
});

earn.rule("clean_line", { when: "race.clean", n: 1, pay: 12, oncePer: "run" });

Other events include player.finished, race.won and race.podium (which count only with another person in the round), lap.completed, coin.collected, drift.boosted and drift.ultra.

#4. Check it with bots

npm test

#How it works

The simulation is @netforge/engine-sim's kart mode: arcade vehicle physics on a 1/1024 grid at 60 Hz. Each tick, velocity splits into forward and sideways parts; the engine pushes the forward part toward top speed, grip bleeds the sideways part (much less while drifting), and steering turns with speed. Your browser predicts your own kart; kart-to-kart bumps run only on the server and the next snapshot corrects them. The client streams the track in chunks of about 40 m within 170 m of the camera, so long circuits stay light. See Netcode and prediction.

The full guide is Build a multiplayer kart racer in the browser.

#Alternatives

• Babylon.js is a full 3D engine for the web with physics plugins and a node material editor. Pick it when you want to build your own vehicle physics and scene from engine primitives.
• PlayCanvas is a WebGL and WebGPU engine with a hosted visual editor. Pick it when your team wants to build tracks and scenes in an editor.
• Net Forge fits when you want an eight-player kart racer with drift, boosts, laps, prediction and bots already working, and circuits you declare as data.

#FAQ

#How does drifting work in the kart racer?

Hold Space or Shift while steering through a bend. The mini-turbo charges in three tiers (blue, orange, purple) and fires a 0.5, 0.9 or 1.4 s boost when you release.

#Do karts collide with each other?

Yes, on the server. Your browser predicts your own kart alone, and the next snapshot corrects your position after a bump.

#How many players can race?

Up to eight per room. Seat bots fill the grid up to players.bots (six in the template) and leave as people join.

#Can I design my own track?

Yes. A track is a list of control points in metres plus width, laps, boost pads and coin rows. Add it to tracks; the room draws one circuit per round.

#How are laps counted?

Through four quarter checkpoints in order. Skipping a checkpoint does not count the lap.