Code:
For i = 1 To 30 Step 1
For j = 1 To 84 Step 1
If Cells(i + 1, j).Interior.ColorIndex = xlNone Then
If Cells(i, j) = "X" Then
Cells(i + 1, j + 1).Interior.ColorIndex = 3
Cells(i - 1, j - 1).Interior.ColorIndex = 3
Cells(i, j + 1).Interior.ColorIndex = 3
Cells(i + 1, j).Interior.ColorIndex = 3
Cells(i + 1, j - 1).Interior.ColorIndex = 3
Cells(i - 1, j + 1).Interior.ColorIndex = 3
Cells(i - 1, j).Interior.ColorIndex = 3
Cells(i, j - 1).Interior.ColorIndex = 3
Cells(i + 2, j + 2).Interior.ColorIndex = 3
Cells(i - 2, j - 2).Interior.ColorIndex = 3
Cells(i, j + 2).Interior.ColorIndex = 3
Cells(i + 2, j).Interior.ColorIndex = 3
Cells(i + 2, j - 2).Interior.ColorIndex = 3
Cells(i - 2, j + 2).Interior.ColorIndex = 3
Cells(i - 2, j).Interior.ColorIndex = 3
Cells(i, j - 2).Interior.ColorIndex = 3
Cells(i + 1, j + 2).Interior.ColorIndex = 3
Cells(i + 1, j - 2).Interior.ColorIndex = 3
Cells(i + 2, j + 1).Interior.ColorIndex = 3
Cells(i + 2, j - 1).Interior.ColorIndex = 3
Cells(i - 1, j + 2).Interior.ColorIndex = 3
Cells(i - 1, j - 2).Interior.ColorIndex = 3
Cells(i - 2, j + 1).Interior.ColorIndex = 3
Cells(i - 2, j - 1).Interior.ColorIndex = 3
Else: chb1.Value = False
End If
End If
Next j
Next i