So I've been merging all my DOS games (from GOG and retail) into one big DOS folder, and my plan is to create a Inno Installer for the whole lot.

At the moment in game conf files it has the location I have installed them on this PC ie 'mount c "d:\dos\games\blood' obviously if I install them on another PC for example my Laptop it would go into c:\dos\games\blood but because the conf files contain d:\dos\games\blood i'd have to edit each one manually.

Is there a way to get it to set that to where ever it gets installed to? (Kinda like how GOG do their Dosbox installers.)

I don't know if this is exactly what you wanted, but I've done similar things with Notepad++.
You can just tag 50-70 CONF files and open them with Notepad++, then go to Search -> Replace... (Ctrl+H),
there you can replace d:\dos\games\ with c:\dos\games\ and click on the Replace with all opened documents option, after that you can save all the changes at once.

That's not quite what I'm after, but its a good idea. (One I didn't think of.) I'll use that for the few batch files that I have to launch the games, and if its not possible to change the CONF files via setup I'll do it that way thanks.

It is possible to call the Gog installers from within Inno Setup. You don't even have to add the Gog setups
to the Files section. They can be left external and called like so:

[Run]
{src}\setup_across_the_rhine_1.0_(38244).exe

I know I can call GOG installers, but I don't want to use them. As I dislike them also my main goal from this is to fix the bad coding that GOG has in their CONF files, to only use and have one DOSBox install, and to apply any fixes that I like (such as filling the screen.)

Plus its not just GOG versions of games that I'm adding to it as I have a lot of DOS retail as well.

Had a thought of doing something similar, but it’s a huge outlay of resource. Ideally you want GOG to have one version of dosbox/scumm/etc. and all the games work on it. Perhaps as a separate download, so you could in stall the base package, then the other installers just contain the game and dump it to a given setup. Never going to happen of course. Thankfully size is not huge for these.

I would create an own installer for each game.
In my super installer I would call all these installers in the [Run] section.
In the single installers the game location can be specified on the dir Page, stored in the {app} variable.
In the [code] section of each single installer I would create a conf file by using {app} as game directory.

Never heard of that command is it limited to DOSBox or will it work for Command Prompt as well? It just takes time as you have to edit each conf file and merge them as GOG seems to like to have a few rather than just a menu and one.

It's a Windows command that operates on the NTFS file system level. You type it in once under Windows Command Line (not DOSBox) and it creates a permanent file-system level junction that's visible in everything (Windows Explorer, DOS, DOSBox, 3rd party programs, etc) after that.

I went through my DOS collection last year and did what nightcraw1er.488 suggested above - I just had one single "central" DOSBox install and then went through every DOS game I own, added a .conf file to each game folder pointing to C:\Games\DOS\nameofgame, added a custom .map file to game folder's for those that I added controller support to, added an icon, Start Menu shortcut calling DOSBox with the game's specific .conf (eg, "C:\Program Files (x86)\DOSBox\DOSBox.exe" -conf C:\Games\DOS\Dune\Dune.conf -noconsole -exit), and then simply zipped the lot up with an install.bat file that unzips them all to C:\Games\DOS and copies the pre-made *.lnk (Start Menu Shortcuts) into "%USERPROFILE%\Start Menu\Programs\DOS Games". All the games (over 200) get installed at once complete with Start Menu Shortcuts put in the right place and pre tweaked settings & controller support (for platformers). And if I ever need to move location, I would just use a junction as mentioned above. True, though for many games it's often the conf with "single" in its name that contains the launch command with the others often being very generic cut & paste stuff.