anchor.diff:  :iwad_plutonia
   REM --------------------------------------------------------------------------------------------------------------------
   REM # are we looking for "Final DOOM: The Plutonia Experiment"?
  -IF NOT /I "%IWAD%" == "PLUTONIA.WAD" GOTO :iwad_check
  +IF /I NOT "%IWAD%" == "PLUTONIA.WAD" GOTO :iwad_check
   
   REM # is Steam : Final DOOM installed?
   CALL :reg "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Steam App 2290" "InstallLocation"
  
positive.code: :pwad_master
  REM --------------------------------------------------------------------------------------------------------------------
  REM # are we looking for "Master Levels for DOOM II"?
  IF NOT /I "%PWAD:~0,7%" == "MASTER\" GOTO :pwad_missing
  
  REM # extract the WAD name from that
  SET "WAD=%PWAD:~8%"
  
negative.code: PAUSE
  EXIT /B 1
  
  :iwad_freedoom
  REM # if this was DOOM or DOOM2, we could use FreeDOOM instead
  SET "FREEDOOM="
  REM # TODO: check these files exist too
  