Bueno después de buscar en vano como superponer forms en juegos de pantallas completa  y no encontrar nada, Me resigne a usar la api q Comparti hace tiempo : VB.NET Overlay in Games Full Screen

ups, no xd. ahora lo pruebo. tal vez mañana. y edito este pots para decir como me fue.

oie tu programas en c++ no? seria genial que se agregara compatibilidad con directx 10 y 11 a esa api xd . es solo un comentario.

Por cierto gracias por comentar

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Edición, Probé el code que me pusiste. pero no funciono.

A continuación lo q hice:

Clase - ACCENTPOLICY.vb

Imports System
 
Public Class ACCENTPOLICY
 
    Public nAccentState As Integer
 
    Public nFlags As Integer
 
    Public nColor As Integer
 
    Public nAnimationId As Integer
End Class
 
Public Class WINCOMPATTRDATA
 
    Public nAttribute As Integer
 
    Public pData As Object
 
    Public ulDataSize As UInteger
End Class
 
Public Class Funcs
 
    Public Delegate Function pSetWindowCompositionAttribute(ByVal UnnamedParameter As System.IntPtr, ByVal UnnamedParameter2 As WINCOMPATTRDATA) As Boolean
 
 
    Friend Declare Function SetWindowCompositionAttribute Lib "user32.dll" (ByVal UnnamedParameter As System.IntPtr, ByVal UnnamedParameter2 As WINCOMPATTRDATA) As Boolean
 
    Public Shared Sub SetWindowTransparent(ByVal hWnd As IntPtr)
        Dim hModule As IntPtr = New IntPtr
        If hModule Then
            Dim SetWindowCompositionAttribute As pSetWindowCompositionAttribute = SetWindowCompositionAttribute
            If (Not (SetWindowCompositionAttribute) Is Nothing) Then
                Dim policy As ACCENTPOLICY = New ACCENTPOLICY
                ' ACCENT_ENABLE_TRANSPARENTGRADIENT=2...
                Dim data As WINCOMPATTRDATA = New WINCOMPATTRDATA
                ' WCA_ACCENT_POLICY=19
                SetWindowCompositionAttribute(hWnd, data)
            End If
 
        End If
 
    End Sub
 
End Class
 
 

Form1.vb

Imports WindowsApplication4.ACCENTPOLICY
 
Public Class Form1
 
 
    Public Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal Classname As String, ByVal WindowName As String) As IntPtr
    Public Declare Function GetWindowThreadProcessId Lib "user32" (ByVal hWnd As IntPtr, ByRef lpdwProcessId As Integer) As Integer
    Public Declare Function OpenProcess Lib "kernel32" (ByVal dwDesiredAccess As Integer, ByVal bInheritHandle As Integer, ByVal dwProcessId As Integer) As IntPtr
    Public Declare Function CloseHandle Lib "kernel32" (ByVal hObject As IntPtr) As Integer
    Public Const PROCESS_VM_ALL As Integer = &H1F0FFF
    Public hWnd As IntPtr, pHandle As IntPtr, processID As Integer
    Const ProcessName As String = "hl2"
 
 
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
 
        If ProcessHack() = 1 Then
            WindowsApplication4.Funcs.SetWindowTransparent(pHandle)
        End If
 
    End Sub
 
    Private Function ProcessHack() As Integer
        Dim proc As Process() = Process.GetProcessesByName(ProcessName)
        Dim windowname As String
        windowname = proc(0).MainWindowTitle
        hWnd = FindWindow(vbNullString, windowname)
        GetWindowThreadProcessId(hWnd, processID)
        pHandle = OpenProcess(PROCESS_VM_ALL, 0, processID)
        If hWnd = 0 Then
            Return 0
        Else
            Return 1
        End If
    End Function
 
 
End Class

Bueno al menos lo intente .-.