# Physilinks

Physilinks is a browser-based physics linking game built with Matter.js. Match and chain same-colored falling balls; link enough to clear them and rack up points.

## Play instructions
- Open `index.html` in a modern browser (desktop or mobile touch).
- Choose a scene from the selector (changes gravity, obstacles, spawn rate, palette, ball size). Switching scenes restarts the run.
- Click/touch a ball to start a chain; drag through balls of the same color to add them. Drag back to the previous ball to undo the last link.
- Release: if the chain length is below the minimum, links vanish; if it meets/exceeds the minimum, linked balls are cleared and you score `10 × length²` (popup shows the gain).
- The top is open; if a new ball cannot enter because the entry is blocked, the run ends. The overlay shows final score with a restart button.
- Pause/resume with the button or `Esc`. HUD shows spawn rate, min link, chain length, score, per-scene high score, and palette legend.

## Tech notes
- **Engine**: Matter.js (via CDN). Canvas rendering with custom overlays for HUD, pause, game over, and score popups.
- **Scenes**: Defined in `main.js` as an array of presets (config + `createBodies` factory). Applying a scene updates gravity, spawn rate, ball radius, palette, and static bodies, then restarts the game.
- **Physics entities**: Falling balls (`Bodies.circle`) with gentle restitution/friction; static boundaries/obstacles per scene. The top is open; sides and floor are static bodies.
- **Input**: Pointer/touch events mapped to scene coords; chain state tracks bodies and a dashed preview line to the pointer. Undo by dragging back to the previous node.
- **Scoring**: `10 × length²` per cleared chain. Score popup rendered as DOM element near release point.
- **Persistence**: Per-scene high score stored in `localStorage` under `physilinks-highscore-<sceneId>`; loaded on scene change; HUD shows current scene's best.
- **Game loop**: Single Matter runner started once. Pause sets `engine.timing.timeScale = 0` and stops spawning; resume resets time scale and spawner. Game over stops spawner, freezes physics, and shows overlay.
- **Lose detection**: Spawned balls monitor entry; if they remain near the spawn zone with negligible velocity after a short delay, the run is over.

## Development quick start
- No build step. Open `index.html` directly in the browser.
- Key files: `index.html` (layout/styles), `main.js` (game logic).
- Adjust or add scenes in `main.js` by extending the `scenes` array with config and a `createBodies(width, height)` function.