{ 
  Make your application like a game. Full Screen. 
  Disable all of the system keys. 
} 

procedure TForm1.FormCreate(Sender: TObject); 
var 
  HTaskbar: HWND; 
  OldVal: LongInt; 
begin 
  try 
    // Find handle of TASKBAR 
    HTaskBar := FindWindow('Shell_TrayWnd', nil); 
    // Turn SYSTEM KEYS off, Only Win 95/98/ME 
    SystemParametersInfo(97, Word(True), @OldVal, 0); 
    // Disable the taskbar 
    EnableWindow(HTaskBar, False); 
    // Hide the taskbar 
    ShowWindow(HTaskbar, SW_HIDE); 
  finally 
    with Form1 do  
    begin 
      BorderStyle := bsNone; 
      FormStyle   := fsStayOnTop; 
      Left        := 0; 
      Top         := 0; 
      Height      := Screen.Height; 
      Width       := Screen.Width; 
    end; 
  end 
end; 

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction); 
var 
  HTaskbar: HWND; 
  OldVal: LongInt; 
begin 
  //Find handle of TASKBAR 
  HTaskBar := FindWindow('Shell_TrayWnd', nil); 
  //Turn SYSTEM KEYS Back ON, Only Win 95/98/ME 
  SystemParametersInfo(97, Word(False), @OldVal, 0); 
  //Enable the taskbar 
  EnableWindow(HTaskBar, True); 
  //Show the taskbar 
  ShowWindow(HTaskbar, SW_SHOW); 
end;