fix: physics tunneling and update fruit stats to community standard

Fix fruits falling through the floor by replacing single-step physics
with fixed-timestep sub-stepping (16.67ms steps, max 5 per frame).
Add escaped-body cleanup as safety net. Tune physics constants for
better feel (higher density, more bounce, less float).

Update fruit radii to match the community-standard ratios (TomboFry/
moonfloof clones) scaled to our 400px container. Update colors to
match real fruit appearances. Fix "Grapes" → "Grape" per wiki.

docs/gameplay.md

@@ -7,20 +7,22 @@
 
 ## Fruit Chain
 
-Cherry → Strawberry → Grapes → Dekopon → Persimmon → Apple → Pear → Peach → Pineapple → Melon → Watermelon
+Cherry → Strawberry → Grape → Dekopon → Persimmon → Apple → Pear → Peach → Pineapple → Melon → Watermelon
 
 | Tier | Fruit | Radius | Color | Merge Points |
 |------|-------|--------|-------|-------------|
 | 0 | Cherry | 12px | Red | 1 |
-| 1 | Strawberry | 16px | Light Red | 3 |
-| 2 | Grapes | 20px | Purple | 6 |
-| 3 | Dekopon | 26px | Orange | 10 |
-| 4 | Persimmon | 32px | Dark Orange | 15 |
-| 5 | Apple | 36px | Red | 21 |
-| 6 | Pear | 42px | Green-Yellow | 28 |
-| 7 | Peach | 48px | Peach | 36 |
-| 8 | Pineapple | 57px | Yellow | 45 |
-| 9 | Melon | 64px | Green | 55 |
-| 10 | Watermelon | 77px | Dark Green | 66 |
+| 1 | Strawberry | 17px | Pink-Red | 3 |
+| 2 | Grape | 21px | Purple | 6 |
+| 3 | Dekopon | 29px | Orange | 10 |
+| 4 | Persimmon | 33px | Orange-Red | 15 |
+| 5 | Apple | 37px | Red | 21 |
+| 6 | Pear | 44px | Yellow-Green | 28 |
+| 7 | Peach | 50px | Peach | 36 |
+| 8 | Pineapple | 67px | Yellow | 45 |
+| 9 | Melon | 83px | Green | 55 |
+| 10 | Watermelon | 100px | Dark Green | 66 |
+
+Radii are scaled from the [community-standard values](https://github.com/TomboFry/suika-game) (24–192px) to fit the 400px container. Points match the Nintendo Switch scoring.
 
 Only the 5 smallest fruits (Cherry through Persimmon) appear as drop candidates. When two Watermelons merge, they disappear and award 66 bonus points.

src/constants.js

@@ -15,12 +15,17 @@ export const DANGER_LINE_Y = CONTAINER_Y + 50;
 // Physics
 export const GRAVITY = { x: 0, y: 1.5 };
 export const FRUIT_BODY_OPTIONS = {
-  restitution: 0.2,
-  friction: 0.5,
-  frictionAir: 0.01,
-  density: 0.001,
+  restitution: 0.3,
+  friction: 0.3,
+  frictionAir: 0.02,
+  frictionStatic: 0.5,
+  density: 0.003,
 };
 
+// Fixed physics step: run sub-steps at this interval to prevent tunneling
+export const PHYSICS_STEP_MS = 1000 / 60; // ~16.67ms
+export const MAX_SUB_STEPS = 5; // cap sub-steps to avoid spiral of death
+
 // Timing
 export const DROP_COOLDOWN_MS = 500;
 export const NEW_FRUIT_GRACE_MS = 1000;

src/fruits.js

@@ -1,15 +1,18 @@
+// Community-standard fruit stats (TomboFry/moonfloof clones, Suika Game Wiki).
+// Radii scaled from the standard (24..192) by 0.52 to fit our 400px container.
+// Points match the Nintendo Switch scoring: 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66.
 export const FRUITS = [
-  { tier: 0, name: 'Cherry', radius: 12, color: '#E74C3C', points: 1 },
-  { tier: 1, name: 'Strawberry', radius: 16, color: '#FF6B6B', points: 3 },
-  { tier: 2, name: 'Grapes', radius: 20, color: '#9B59B6', points: 6 },
-  { tier: 3, name: 'Dekopon', radius: 26, color: '#F39C12', points: 10 },
-  { tier: 4, name: 'Persimmon', radius: 32, color: '#E67E22', points: 15 },
-  { tier: 5, name: 'Apple', radius: 36, color: '#E74C3C', points: 21 },
-  { tier: 6, name: 'Pear', radius: 42, color: '#A8D648', points: 28 },
-  { tier: 7, name: 'Peach', radius: 48, color: '#FDCB6E', points: 36 },
-  { tier: 8, name: 'Pineapple', radius: 57, color: '#F1C40F', points: 45 },
-  { tier: 9, name: 'Melon', radius: 64, color: '#2ECC71', points: 55 },
-  { tier: 10, name: 'Watermelon', radius: 77, color: '#27AE60', points: 66 },
+  { tier: 0, name: 'Cherry', radius: 12, color: '#E8373B', points: 1 },
+  { tier: 1, name: 'Strawberry', radius: 17, color: '#FF6B6B', points: 3 },
+  { tier: 2, name: 'Grape', radius: 21, color: '#7B52AB', points: 6 },
+  { tier: 3, name: 'Dekopon', radius: 29, color: '#FF8C00', points: 10 },
+  { tier: 4, name: 'Persimmon', radius: 33, color: '#E2611C', points: 15 },
+  { tier: 5, name: 'Apple', radius: 37, color: '#C0392B', points: 21 },
+  { tier: 6, name: 'Pear', radius: 44, color: '#C8D44E', points: 28 },
+  { tier: 7, name: 'Peach', radius: 50, color: '#FFBF8C', points: 36 },
+  { tier: 8, name: 'Pineapple', radius: 67, color: '#F5C518', points: 45 },
+  { tier: 9, name: 'Melon', radius: 83, color: '#90C040', points: 55 },
+  { tier: 10, name: 'Watermelon', radius: 100, color: '#3A7D44', points: 66 },
 ];
 
 // Only the 5 smallest fruits can be randomly selected for dropping

src/game.js

@@ -3,6 +3,7 @@ import {
   createWalls,
   createFruitBody,
   addToWorld,
+  removeFromWorld,
   getAllBodies,
   stepEngine,
 } from './physics.js';
@@ -12,10 +13,15 @@ import { clampX } from './input.js';
 import { FRUITS, getRandomDroppableTier } from './fruits.js';
 import {
   CANVAS_WIDTH,
+  CONTAINER_X,
+  CONTAINER_WIDTH,
   CONTAINER_Y,
+  CONTAINER_HEIGHT,
   DANGER_LINE_Y,
   DROP_COOLDOWN_MS,
   NEW_FRUIT_GRACE_MS,
+  PHYSICS_STEP_MS,
+  MAX_SUB_STEPS,
 } from './constants.js';
 
 export class Game {
@@ -25,6 +31,7 @@ export class Game {
     this.mergeHandler = null;
     this.state = null;
     this.lastTime = 0;
+    this.accumulator = 0;
     this.animFrameId = null;
     this.cooldownTimer = null;
     this.init();
@@ -60,8 +67,21 @@ export class Game {
     this.lastTime = time;
 
     if (!this.state.isGameOver) {
-      stepEngine(this.engine, delta);
-      this.mergeHandler.flushMerges();
+      // Fixed-step sub-stepping: accumulate time and run physics in
+      // consistent small steps to prevent tunneling through walls/floor.
+      this.accumulator += delta;
+      const maxAccumulated = PHYSICS_STEP_MS * MAX_SUB_STEPS;
+      if (this.accumulator > maxAccumulated) {
+        this.accumulator = maxAccumulated;
+      }
+
+      while (this.accumulator >= PHYSICS_STEP_MS) {
+        stepEngine(this.engine, PHYSICS_STEP_MS);
+        this.mergeHandler.flushMerges();
+        this.accumulator -= PHYSICS_STEP_MS;
+      }
+
+      this.removeEscapedBodies();
       this.checkGameOver();
     }
 
@@ -93,6 +113,22 @@ export class Game {
     }, DROP_COOLDOWN_MS);
   }
 
+  removeEscapedBodies() {
+    const bodies = getAllBodies(this.engine);
+    const margin = 100;
+    const minX = CONTAINER_X - margin;
+    const maxX = CONTAINER_X + CONTAINER_WIDTH + margin;
+    const maxY = CONTAINER_Y + CONTAINER_HEIGHT + margin;
+
+    for (const body of bodies) {
+      if (body.fruitTier === undefined || body.isStatic) continue;
+      const { x, y } = body.position;
+      if (x < minX || x > maxX || y > maxY) {
+        removeFromWorld(this.engine, body);
+      }
+    }
+  }
+
   checkGameOver() {
     const now = Date.now();
     const bodies = getAllBodies(this.engine);