is it possible to extract all necessary game files from installer without having to install these games onto windows?
because i only need the original game files without dosbox or emulation related stuff for another pc without windows.

Yes. You can use innoextract to unpack the windows installers.

http://constexpr.org/innoextract/

thx, i'll try that.

Note that InnoSetup frequently changes its format in their releases, so sometimes innoextract is not ready yet for the latest version of InnoSetup, or there's no release yet and you have to build it from latest sources on git.

Encountered such problem today with X-Com: Ufo Defense, which had installer created with InnoSetup 5.6.2. Fortunately latest sources of innoextract already had support for it, but not in latest release version.

same problem here, it's august 2019 and still no updated version of innoextract available. i can't even use 7zip to extract which would work with other setup files. so how do i get .wad files out of my ultimate doom 1 and doom 2 + final?

do i really need to install doom 1, doom 2 and final doom on windows pc in order to get these .wad files to my amiga where i want to play these games?

If you haven't seen it yet, innoextract 1.8 has been released since. Also, you can always build it yourself. It doesn't have that many dependencies. Though the Boost libs are often packaged piecemeal.