Registry keys installed by different Windows Doom installers that can be used
to locate IWAD files.

== Collectors Edition ==

Install path can be found from
HKEY_LOCAL_MACHINE\Software\Activision\DOOM Collector's Edition\v1.0\INSTALLPATH

wads are then in
${INSTALL_PATH}\Doom2
${INSTALL_PATH}\Final Doom
${INSTALL_PATH}\Ultimate Doom

== Final Doom ==

Look at 
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall\Final DOOM for Windows 95\UninstallString

The value looks like

C:\Program Files\Path\uninstl.exe /S C:\Program Files\Path

Cut everything after and including "\uninstl.exe /S" to get the install path
WADs are in this install path

== Depths of Doom trilogy ==

=== Doom II for Windows 95 ===

Look at 
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall\Doom II for Windows 95\UninstallString

The value looks like

C:\Program Files\Path\uninstl.exe /S C:\Program Files\Path

Cut everything after and including "\uninstl.exe /S" to get the install path
doom2.wad is in the install path

=== Ultimate Doom ===

Look at 
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall\Ultimate Doom for Windows 95

The value looks like

C:\Program Files\Path\uninstl.exe /S C:\Program Files\Path

Cut everything after and including "\uninstl.exe /S" to get the install path
doom.wad is in the install path

== Chex Quest ==

Look at HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall\Chex® Quest

The value looks like:

C:\Chex\UNWISE.EXE C:\Chex\INSTALL.LOG

Cut everything after and including "\UNWISE.EXE" to get the install path.
chex.wad is in the install path.

== Steam ==

Get the steam install location from:

HKEY_LOCAL_MACHINE\Software\Valve\Steam\InstallPath

IWADs are installed at:

${STEAM}\steamapps\common\doom 2\doom2.wad
${STEAM}\steamapps\common\ultimate doom\doom.wad
${STEAM}\steamapps\common\final doom\tnt.wad
${STEAM}\steamapps\common\final doom\plutonia.wad
${STEAM}\steamapps\common\hexen\base\hexen.wad
${STEAM}\steamapps\common\heretic shadow of the serpent riders\heretic.wad