Sub MidScreenClick()
  Call SendMessage(WindowFromPoint(MidScreenX, MidScreenY), WM_LBUTTONDOWN, ByVal 0&, ByVal 0&)
  Call SendMessage(WindowFromPoint(MidScreenX, MidScreenY), WM_LBUTTONUP, ByVal 0&, ByVal 0&)
End Sub

Property Get MidScreenX()As Long
  MidScreenX = (Screen.Width / Screen.TwipsPerPixelX) / 2
End Sub

Property Get MidScreenY()As Long
  MidScreenY = (Screen.Height / Screen.TwipsPerPixelY) / 2
End Sub

     Dim iCnt%

  ...

  For ... ....
    btData(iCnt)= ....
    iCnt=iCnt+1
  Next
  ...

Function RegWriteBin(ByVal Data As String) As Boolean
  On Error Resume Next
  
      Dim btData() As Byte
      Dim hKey&, r&
      Dim i&

  Data = Replace$(Data, " ", vbNullString)

  If (Len(Data) Mod 2) <> 0 Then Data = Data & "0"

  r = RegCreateKeyEx(HKEY_LOCAL_MACHINE, "Software\MyApp\", 0&, vbNullString, _
                     0&, KEY_ALL_ACCESS, 0&, hKey, REG_CREATED_NEW_KEY)

  If r = ERROR_SUCCESS Then
    ReDim btData(Len(Data) \ 2) As Byte
   
    For i = 1 To (Len(Data) \ 2) Step 2
      btData(i) = Val("&H" & Mid$(Data, i, 2))
    Next
   
    r = RegSetValueEx(hKey, "MyBinValue", 0&, REG_BINARY, btData(0), Len(Data) \ 2)
    r = RegCloseKey(hKey)
   
    RegWriteBin = (r = ERROR_SUCCESS)
  End If
End Function

Function RegReadBin() As String
      Dim btData() As Byte
      Dim lBufferLen&, i&
      Dim hKey&, r&

  r = RegCreateKeyEx(HKEY_LOCAL_MACHINE, "Software\MyApp\", 0&, vbNullString, _
                     0&, KEY_ALL_ACCESS, 0&, hKey, REG_CREATED_NEW_KEY)

  If r = ERROR_SUCCESS Then
    lBufferLen = 2048
    
    ReDim btData(lBufferLen) As Byte
    
    sData = String$(lBufferLen, 0)
    
    r = RegQueryValueExByte(hKey, "MyBinValue", 0&, REG_BINARY, btData(0), lBufferLen)
    
    If r = ERROR_SUCCESS Then
      RegReadBin = Left$(StrConv(btData, vbUnicode), lBufferLen)
    End If
  
    r = RegCloseKey(hKey)
  
  End If
End Function

Function RegWriteBin(ByVal Data As String) As Boolean
      Dim btData() As Byte
      Dim sChar$(), i&
      Dim hKey&, r&

  r = RegCreateKeyEx(HKEY_LOCAL_MACHINE, "Software\MyApp\", 0&, vbNullString, _
                     0&, KEY_ALL_ACCESS, 0&, hKey, REG_CREATED_NEW_KEY)

  If r = ERROR_SUCCESS Then
    sChar = Split(Data, " ")
    ReDim btData(UBound(sChar)) As Byte
    
    For i = 0 To UBound(sChar) - 1
      btData(i) = Val("&H" & sChar(i))
    Next
    
    r = RegSetValueEx(hKey, "MyBinValue", 0&, REG_BINARY, btData(0), UBound(sChar))
    r = RegCloseKey(hKey)
    
    RegWriteBin = (r = ERROR_SUCCESS)
  End If
End Function

Private Declare Function RegCreateKeyEx Lib "advapi32.dll" Alias "RegCreateKeyExA" (ByVal hKey As Long, ByVal lpSubKey As String, ByVal Reserved As Long, ByVal lpClass As String, ByVal dwOptions As Long, ByVal samDesired As Long, ByVal lpSecurityAttributes As Long, phkResult As Long, ByVal lpdwDisposition As Long) As Long

Private Declare Function RegCloseKey Lib "advapi32.dll" (ByVal hKey As Long) As Long

Private Declare Function RegSetValueEx Lib "advapi32.dll" Alias "RegSetValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal Reserved As Long, ByVal dwType As Long, lpData As Byte, ByVal cbData As Long) As Long

Function RegWriteBin(ByVal Data As String) As Boolean
      Dim btData() As Byte
      Dim hKey&, r&

  btData = StrConv(Data, vbFromUnicode)
  
  r = RegCreateKeyEx(HKEY_LOCAL_MACHINE, "Software\MyApp\", 0&, vbNullString, _
                     0&, KEY_ALL_ACCESS, 0&, hKey, REG_CREATED_NEW_KEY)

  If r = ERROR_SUCCESS Then
    r = RegSetValueEx(hKey, "MyBinValue", 0&, REG_BINARY, btData(0), Len(Data))
    r = RegCloseKey(hKey)
    
    RegWriteBin = (r = ERROR_SUCCESS)
  End If
End Function

Option Explicit

Private iCurCol   As Integer
Private iCurLin   As Integer
Private iCurIndex As Integer

Private sLastVal As String

Sub LoadInterface()
      Dim snLeft!, snTop!
      Dim iAddH%, iAddY%
      Dim iLin%, i%

  For i = 1 To 80
    If (i Mod 9) = 0 Then
      iLin = iLin + 1
    End If
    
    Call Load(txtNum(i))
    
    With txtNum(i)
      If (i Mod 3) = 0 Then
        iAddH = (10 * (i Mod 9))
      End If
      
      If (iLin Mod 3) = 0 Then
        iAddY = (10 * (iLin Mod 9))
      End If
      
      snLeft = (.Width * (i Mod 9)) + iAddH
      snTop = iLin * .Height + iAddY
      
      Call .Move(snLeft, snTop)
      
      .Visible = True
    End With
  Next
  
  Width = txtNum(0).Width * 9 + iAddH
  Height = Width
End Sub

Function RightVal(ByVal Col As Integer, ByVal Lin As Integer, ByVal Index As Integer, ByVal Value As Integer) As Boolean
          Dim iIndex%, i%
          Dim iSelIndex%
          Dim iVal%

  iIndex = Index
  
  If (iIndex Mod 9) > 0 Then
    Do While ((iIndex Mod 9) <> 0)
      iIndex = iIndex - 1
    Loop
  End If
  
  For i = iIndex To iIndex + 8
    If txtNum(i) <> vbNullString Then
      If (Val(txtNum(i)) = Value) And (i <> Index) Then
        Exit Function
      End If
    End If
  Next
  
  For i = 0 To 8
    iSelIndex = (i * 9) + Col
    
    If txtNum(iSelIndex) <> vbNullString Then
      If Val(txtNum(iSelIndex)) = Value And (iSelIndex <> Index) Then
        Exit Function
      End If
    End If
  Next
  
  RightVal = True
End Function

Sub HighlightLin(ByVal Col As Integer, ByVal Lin As Integer, ByVal Index As Integer)
          Dim iIndex%, i%
          Dim iSelIndex%
          Dim iVal%

  iIndex = Index
  
  If (iIndex Mod 9) > 0 Then
    Do While ((iIndex Mod 9) <> 0)
      iIndex = iIndex - 1
    Loop
  End If
  
  For i = 0 To 80
    txtNum(i).BackColor = vbWindowBackground
  Next
  
  For i = iIndex To iIndex + 8
    txtNum(i).BackColor = vbCyan
  Next
  
  For i = 0 To 8
    iSelIndex = (i * 9) + Col
    txtNum(iSelIndex).BackColor = vbCyan
  Next
End Sub

Private Sub Form_KeyDown(KeyCode As Integer, Shift As Integer)
  If KeyCode = vbKeyEscape Then End
End Sub

Private Sub Form_Load()
  txtNum(0) = vbNullString
  Call txtNum(0).Move(0, 0, 360, 360)
  BackColor = 0
  
  Call LoadInterface
End Sub

Private Sub txtNum_GotFocus(Index As Integer)
  txtNum(Index).SelStart = 0
  txtNum(Index).SelLength = Len(txtNum(Index))
  
  iCurIndex = Index
  iCurCol = (iCurIndex Mod 9)
  iCurLin = (iCurIndex \ 9)
  
  Call HighlightLin(iCurCol, iCurLin, iCurIndex)
  
  sLastVal = txtNum(Index)
End Sub

Private Sub txtNum_KeyDown(Index As Integer, KeyCode As Integer, Shift As Integer)
  On Error Resume Next
  
  Select Case KeyCode
    Case vbKeyUp:     Call txtNum(Index - 9).SetFocus
    Case vbKeyDown:   Call txtNum(Index + 9).SetFocus
    Case vbKeyLeft:   Call txtNum(Index - 1).SetFocus
    Case vbKeyRight:  Call txtNum(Index + 1).SetFocus
  End Select
End Sub

Private Sub txtNum_LostFocus(Index As Integer)
        Dim i%
        
  If txtNum(Index) = vbNullString Then Exit Sub
  
  iCurCol = (iCurIndex Mod 9)
  iCurLin = (iCurIndex \ 9)
  
  If Not RightVal(iCurCol, iCurLin, iCurIndex, Val(txtNum(Index))) Then
    Call MsgBox("El número ingresado no es correcto", vbExclamation)
    
    txtNum(Index) = sLastVal
  Else
    For i = 0 To 80
      If txtNum(i) = vbNullString Then Exit Sub
    Next
    
    Call MsgBox("Felicitaciones, ganaste!!", vbExclamation)
    Call Clipboard.SetData(Image, vbCFBitmap)
  End If
End Sub