按照snake文档的要求，根据所提供的snake.py代码框架，实现功能。

根据《Snake.docx》文档提供的指南，以下是实现功能的关键步骤：

### 初始化项目环境
1. **安装pygame**:

   pip3 install pygame

### 设置基本参数
1. **屏幕大小和比例**:
- 宽度 (`Width`): 600
- 高度 (`Height`): 600
- 比例 (`Scale`): 30
- 计算公式: `Width = GridWidth * Scale`, `Height = GridHeight * Scale`

2. **颜色定义**:
- 背景颜色 (`BackgroundColor`): (0, 0, 0)
- 文本颜色 (`TextColor`): (255, 255, 255)
- 食物颜色 (`FoodColor`): (255, 0, 0)
- 蛇颜色 (`SnakeColor`): (0, 255, 0)

### 游戏初始化
1. **初始化游戏**:
- 创建 `Game` 类，初始化屏幕和其他必要属性。
- 屏幕属性保存为 `self.Display`。

2. **游戏循环**:
- 监听按键事件，处理退出和方向键。
- 更新游戏状态，绘制帧。

### 实现具体任务
#### Task 1: 单元格上色
1. **实现 `ColourCell` 函数**:

   def ColourCell(self, position, color):
       x, y = position
       rect = pygame.Rect(x * self.Scale, y * self.Scale, self.Scale, self.Scale)
       pygame.draw.rect(self.Display, color, rect)

2. **在 `DisplayFrame` 中调用 `ColourCell`**:

   for cell in snake.Body:
       self.ColourCell(cell, self.SnakeColor)

#### Task 2: Snake 类
1. **初始化 `Snake` 类**:

   class Snake:
       def __init__(self):
           self.Head = [int(GridWidth / 2), int(GridHeight / 2)]
           self.Body = [self.Head]
           self.PreviousCell = None

2. **在 `Play` 函数中创建蛇实例**:

   snake = Snake()

#### Task 3: 移动
1. **实现 `Move` 函数**:

   def Move(self, direction):
       if direction == "Left":
           self.Head[0] -= 1
       elif direction == "Right":
           self.Head[0] += 1
       elif direction == "Up":
           self.Head[1] -= 1
       elif direction == "Down":
           self.Head[1] += 1
       self.PreviousCell = self.Body[-1].copy()
       self.Body.insert(0, self.Head.copy())
       self.Body.pop()

2. **在 `Play` 中处理按键事件**:

   keys = pygame.key.get_pressed()
   if keys[pygame.K_LEFT]:
       snake.Move("Left")
   elif keys[pygame.K_RIGHT]:
       snake.Move("Right")
   elif keys[pygame.K_UP]:
       snake.Move("Up")
   elif keys[pygame.K_DOWN]:
       snake.Move("Down")

#### Task 4: 时间和速度
1. **初始化时钟**:

   clock = pygame.time.Clock()
   GameSpeed = 15

2. **修改游戏循环**:

   running = True
   started = False
   while running:
       for event in pygame.event.get():
           if event.type == pygame.QUIT:
               running = False
           elif event.type == pygame.KEYDOWN and not started:
               started = True
       if started:
           snake.Move(current_direction)
           # 其他逻辑
       self.DisplayFrame()
       pygame.display.flip()
       clock.tick(GameSpeed)

#### Task 5: 食物
1. **实现 `NewFood` 函数**:

   def NewFood(self):
       self.FoodPosition = [random.randint(0, GridWidth - 1), random.randint(0, GridHeight - 1)]

2. **初始化时调用 `NewFood`**:

   game.NewFood()

3. **在 `DisplayFrame` 中绘制食物**:

   self.ColourCell(game.FoodPosition, self.FoodColor)

4. **实现 `EatenFood` 函数**:

   def EatenFood(self):
       return self.Head == game.FoodPosition

5. **在游戏循环中检查食物**:

   if snake.EatenFood():
       game.NewFood()
       snake.Body.append(snake.PreviousCell)
       score += 1

#### Task 6: 游戏结束
1. **实现 `OffScreen` 和 `EatenSelf` 函数**:

   def OffScreen(self):
       return self.Head[0] < 0 or self.Head[0] >= GridWidth or self.Head[1] < 0 or self.Head[1] >= GridHeight

   def EatenSelf(self):
       return self.Head in self.Body[1:]

2. **在游戏循环中检查游戏结束条件**:

   if snake.OffScreen() or snake.EatenSelf():
       running = False

#### Task 7: 文本显示
1. **在 `DisplayFrame` 中显示分数**:

   font = pygame.font.Font(None, 36)
   text = font.render(f"Score: {score}", True, self.TextColor)
   self.Display.blit(text, (10, 10))

2. **在游戏结束时显示信息**:

   if not running:
       self.Display.fill(self.BackgroundColor)
       text = font.render("Game Over", True, self.TextColor)
       self.Display.blit(text, (GridWidth // 2 - 50, GridHeight // 2 - 20))
       text = font.render(f"Score: {score}", True, self.TextColor)
       self.Display.blit(text, (GridWidth // 2 - 50, GridHeight // 2 + 20))
       pygame.display.flip()
       waiting_for_key = True
       while waiting_for_key:
           for event in pygame.event.get():
               if event.type == pygame.QUIT:
                   pygame.quit()
                   sys.exit()
               elif event.type == pygame.KEYDOWN:
                   waiting_for_key = False
                   running = True
                   score = 0
                   snake = Snake()
                   game.NewFood()

通过以上步骤，你可以完成《Snake.docx》文档中描述的所有功能。祝你编程愉快！