snake

private void timer1_Tick(object sender, EventArgs e)    //Called every so many milliseconds depending on the interval which is set determined by the length of the snake (to increase difficulty of game, longer snake = faster update)
        {
            SnakeLengthLabel.Text = snakeLength.ToString();

            switch (changeToDirection) //Checks if the snake can move in the direction of the arrow key pressed
            {
                case "left":
                    if (direction != "right")
                    {
                        direction = "left";
                    }
                    break;
                case "right":
                    if (direction != "left")
                    {
                        direction = "right";
                    }
                    break;
                case "up":
                    if (direction != "down")
                    {
                        direction = "up";
                    }
                    break;
                case "down":
                    if (direction != "up")
                    {
                        direction = "down";
                    }
                    break;
            }
            switch (direction) //Changes snakes direction
            {
                case "left":
                    snakeXPos -= 1;
                    checkIFOffBoard();
                    Box[snakeXPos, snakeYPos].BackColor = Color.Red;
                    break;
                case "right":
                    snakeXPos += 1;
                    checkIFOffBoard();
                    Box[snakeXPos, snakeYPos].BackColor = Color.Red;
                    break;
                case "up":
                    snakeYPos -= 1;
                    checkIFOffBoard();
                    Box[snakeXPos, snakeYPos].BackColor = Color.Red;
                    break;
                case "down":
                    snakeYPos += 1;
                    checkIFOffBoard();
                    Box[snakeXPos, snakeYPos].BackColor = Color.Red;
                    break;
            }

            for (int i = 0; i <= 9; i++)    //Checks if the snake has eaten a food
            {
                if (snakeXPos == foodXPos[i] && snakeYPos == foodYPos[i])
                {
                    snakeLength += 1;
                    SnakeLengthLabel.Text = snakeLength.ToString();
                    newFood();
                }
            }

            for (int i = 1; i < 100; i++) //Checks if the snake has collided with itself
            {
                if (snakeXPos == snakeXPositions[i] && snakeYPos == snakeYPositions[i])
                {
                    EndGameLabel.Text = "You Lost!" + Environment.NewLine + Environment.NewLine + "The snake collided with itself" + Environment.NewLine + Environment.NewLine + "Click to play again";
                    endGame();
                }
            }

            if (snakeLength < 20) //Increases the snakes movement speed depending on its length (shorter timer interval = faster speed)
            {
                timer1.Interval = 500 - snakeLength * 25;
            }

            for (int i = 99; i >= 1; i--) // v Makes the snakes body follow the path the head of the snake took
            {
                if (i < snakeLength)
                {
                    snakeXPositions[i + 1] = snakeXPositions[i];
                    snakeYPositions[i + 1] = snakeYPositions[i];
                }
                else if (i > snakeLength)
                {
                    snakeXPositions[i] = -1;
                    snakeYPositions[i] = 0;
                }
            }                           // ^

            snakeXPositions[1] = snakeXPos;
            snakeYPositions[1] = snakeYPos;

            for (int y = 0; y < 30; y++) // v Updates snakes position
            {
                for (int x = 0; x < 30; x++)
                {
                    if (Box[x, y].BackColor != Color.Blue)
                    {
                        Box[x, y].BackColor = Color.Black;
                    }


                    if (BoxBorders.Checked == true)
                    {
                        Box[x, y].BorderStyle = BorderStyle.FixedSingle;
                    }
                    else
                    {
                        Box[x, y].BorderStyle = BorderStyle.None;
                    }

                }
            }

            for (int i = 1; i < 100; i++)
            {
                if (snakeXPositions[i] != -1)
                {
                    Box[snakeXPositions[i], snakeYPositions[i]].BackColor = Color.Red;
                }

            }                           // ^
        }