Mine

Public Class frmMain
    'Declare Global for Random Generator, Random Number, Number of Guesses & an Array of the Guesses
    Dim numRandom As New Random
    Dim numAnswer As Integer
    Dim numGuesses As Integer = 0
    Dim aryGuesses() As Integer

    'On Load
    Private Sub frmMain_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        'Generate Random Number, and Blank the Guesses Label
        numAnswer = numRandom.Next(1, 101)
        lblGuesses.Text = ""
    End Sub

    'Validate Guess before Entry
    Private Sub txtGuess_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles txtGuess.TextChanged
        'Is it Numeric ?
        If IsNumeric(txtGuess.Text) = False Then
            ErrorProvider.SetError(txtGuess, " Your guess must Numeric ")
            btnGuess.Enabled = False
            'Is it Greater Than or Equle to 1 ?
        ElseIf 1 >= txtGuess.Text Then
            ErrorProvider.SetError(txtGuess, " Your guess must be greater than, or equle to 1 ")
            btnGuess.Enabled = False
            'Is is Less Than or Equle to 100 ?
        ElseIf 100 <= txtGuess.Text Then
            ErrorProvider.SetError(txtGuess, " Your guess must be less than, or equle to 100 ")
            btnGuess.Enabled = False
            'Is it a Unique number ?
        ElseIf lstAnswers.Items.Contains(txtGuess.Text) = True Then
            ErrorProvider.SetError(txtGuess, " You cannot guess the same number again ")
            btnGuess.Enabled = False
        Else 'Allow the Guess
            ErrorProvider.SetError(txtGuess, "")
            btnGuess.Enabled = True
        End If
    End Sub

    'Reset Button
    Private Sub btnReset_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnReset.Click
        'Reset the Array, ListBox, TextBox, Label, Button, Picture, Number of Guesses, and Generate new Random Number
        Array.Clear(aryGuesses, 0, numGuesses)
        lstAnswers.DataSource = aryGuesses
        txtGuess.Clear()
        lblGuesses.Text = ""
        txtGuess.Enabled = True
        btnGuess.Enabled = False
        pctWrong.Visible = False
        numAnswer = numRandom.Next(1, 101)
        numGuesses = 0
    End Sub

    'Guess
    Private Sub btnGuess_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnGuess.Click
        'Is the guess the Answer ? Then Show it.
        If txtGuess.Text = numAnswer Then
            pctWrong.Visible = True
            pctWrong.ImageLocation = "tick.png"
            btnGuess.Enabled = False
            txtGuess.Enabled = False
            'Is is Greater Than ? Indicate it through image and Add to Answers List
        ElseIf txtGuess.Text > numAnswer Then
            ReDim Preserve aryGuesses(numGuesses)
            aryGuesses(numGuesses) = txtGuess.Text
            pctWrong.Visible = True
            pctWrong.ImageLocation = "arrow_down.png"
        Else 'Is is Less Than ? Indicate it through image and Add to Answers List
            ReDim Preserve aryGuesses(numGuesses)
            aryGuesses(numGuesses) = txtGuess.Text
            pctWrong.Visible = True
            pctWrong.ImageLocation = "arrow_up.png"
        End If

        'Add one to the Number of Guesses
        numGuesses = numGuesses + 1

        'If you have made 10 guesses then end the game, otherwise just display the number.
        If numGuesses = 10 Then
            btnGuess.Enabled = False
            lblGuesses.Text = "Game Over"
        Else
            lblGuesses.Text = "Guess Number: " & numGuesses & " of 10"
        End If

        'Display Answer in ListBox
        lstAnswers.DataSource = aryGuesses
    End Sub
End Class