如何在简单的贪吃蛇游戏中添加结束画面?

我按照教程制作了一个简单的贪吃蛇游戏，并对其进行了一些修改。当你打开html文件时，游戏立即开始，这很好，但我想为游戏添加一个结尾。当你到达一定数量的点数时，我希望游戏停止循环，也许会出现一个结束画面，但现在我似乎已经明白了。如果有人能给我指出正确的方向，我会非常感激。

//constants
var COLS=26, ROWS=26;
// IDs
var EMPTY=0, SNAKE=1, FRUIT=2;
// directions
var LEFT=0, UP=1, RIGHT=2, DOWN = 3;
// Keykoder
var KEY_LEFT=37, KEY_UP=38, KEY_RIGHT=39, KEY_DOWN = 40;
var soundEfx;
var soundLoad = "smask2.mp3"
var grid = {
width: null,
height: null,
_grid: null,

init: function(d, c, r) {
this.width = c;
this.height = r;
this._grid = [];
for (var x=0; x < c; x++) {
this._grid.push([]);
for (var y=0; y < r; y++) {
this._grid[x].push(d);
}
}
},
set: function(val, x, y) {
this._grid[x][y] = val;
},
get: function(x, y) {
return this._grid[x][y];
}
}
var snake = {
direction: null,
last: null,
_queue: null,

init: function(d, x, y) {
this.direction = d;
this._queue = [];
this.insert(x, y);
},
insert: function(x, y) {
this._queue.unshift({x:x, y:y});
this.last = this._queue[0];
},
remove: function() {
return this._queue.pop();
}
}
function setFood() {
var empty = [];
for (var x=0; x < grid.width; x++) {
for (var y=0; y < grid.height; y++) {
if (grid.get(x, y) === EMPTY) {
empty.push({x:x, y:y});
}
}
} 
var randpos = empty[Math.floor(Math.random()*empty.length)];
grid.set(FRUIT, randpos.x, randpos.y);
}

// Game objects
var canvas, ctx, keystate, frames, score;
function main() {
canvas = document.createElement("canvas");
canvas.width = COLS*20;
canvas.height = ROWS*20;
ctx = canvas.getContext("2d");
document.body.appendChild(canvas);
ctx.font ="12px Helvetica";
frames = 0;
keystate = {};
document.addEventListener("keydown", function(evt)
                      {
 keystate[evt.keyCode] = true;
 });
document.addEventListener("keyup", function(evt)
                     {
 delete keystate[evt.keyCode];
})
init();
loop();
}
function init() {
score = 0;
grid.init(EMPTY, COLS, ROWS);
var sp = {x:Math.floor(COLS/2), y:ROWS-1};
snake.init(UP, sp.x, sp.y);
grid.set(SNAKE, sp.x, sp.y);
setFood();
}
function loop() {
update();
draw();
 window.requestAnimationFrame(loop, canvas);
}
function update() {
frames++;
 if (keystate[KEY_LEFT] && snake.direction !== RIGHT)  snake.direction        =    LEFT;
if (keystate[KEY_UP] && snake.direction !== DOWN) snake.direction = UP;
if (keystate[KEY_RIGHT] && snake.direction !== LEFT) snake.direction = RIGHT;
 if (keystate[KEY_DOWN] && snake.direction !== UP) snake.direction = DOWN;
 if (frames%5 === 0) {
    var nx = snake.last.x;
    var ny = snake.last.y;
    switch (snake.direction) {
        case LEFT:
            nx--;
            break;
        case UP:
            ny--;
            break;
        case RIGHT:
            nx++;
            break;
        case DOWN:
            ny++;
            break;
    }
    if (0 > nx || nx > grid.width-1 ||
        0 > ny || ny > grid.height-1 ||
       grid.get(nx, ny) === SNAKE
       )
        {
            return init();
        }
    if (grid.get(nx, ny) === FRUIT) {
        var tail = {x:nx, y:ny};
        score++;
        setFood();
        soundEfx.play();
    } else {
    var tail = snake.remove();
    grid.set(EMPTY, tail.x, tail.y);
    tail.x = nx;
    tail.y = ny;
    }
    grid.set(SNAKE, tail.x, tail.y);
    snake.insert(tail.x, tail.y);
 }
}
function draw() {
 var tw = canvas.width/grid.width;
 var th = canvas.height/grid.height;
 soundEfx = document.getElementById("soundEfx");
 for (var x=0; x < grid.width; x++) {
 for (var y=0; y < grid.height; y++) {
 switch (grid.get(x, y)) {
 case EMPTY:
 ctx.fillStyle = "#F8F8FF";
 break;
 case SNAKE:
 ctx.fillStyle = "#4682B4";
 break;
 case FRUIT:
 ctx.fillStyle = "#DC143C";
 break;
}
 ctx.fillRect(x*tw, y*th, tw, th);
}
}
ctx.fillStyle = "#000"
ctx.fillText("POÄNG: " + score, 10, canvas.height-10);
}

main();