July 21, 20262 min read

Building Chalky: Making a Darts App That Works Without Bar Wi-Fi

#MobileApp#RetroNerd#ReactNative

The short version

How I built an offline darts scoring tool for noisy pubs, so your score never gets lost when cellular signal drops out.

Darts in a crowded pub is all about rhythm. You throw three darts, tap the screen, and hand the phone to your friend. But most phone apps try to talk to a cloud server every time you tap a button. In a cellar bar with thick brick walls, that means spinning loading wheels and lost scores.

text

[ Tap Triple 20 ] --> ( Update Screen Immediately )
                                 |
                                 v
                     ( Save to Phone Storage )
                                 |
                                 v
                     ( Sync to Cloud Later )

How the Chalky Engine Works

I built Chalky using React Native and Expo to solve this exact problem. Here is how the scoring loop stays super fast:

**Zero Loading Screens:** Every tap updates the screen in less than a millisecond.

**Saved Locally First:** The stats are written straight to your phone's memory.

**Background Sync:** The app only syncs with the internet when you actually have good Wi-Fi.

typescript

type GameState = {
  playerScores: Record<string, number>;
  throwHistory: Array<{ score: number; multiplier: number }>;
};

// A simple reducer function to handle score taps
function scoreReducer(state: GameState, action: { score: number; multiplier: number }): GameState {
  const points = action.score * action.multiplier;
  return {
    ...state,
    playerScores: {
      ...state.playerScores,
      current: (state.playerScores.current || 0) + points,
    },
    throwHistory: [...state.throwHistory, action],
  };
}

The Takeaway

You don't need a huge cloud database just to track a game of Cricket darts with your friends. By keeping the code simple and running everything on the phone first, the app stays fast and fun even in the basement of a noisy bar.

Brian Franke

brian@coasterlogic.com