I am trying to launch the game but it's telling me it requires the CD to play (see attached screenshot).

The problem is gone after uninstalling and reinstalling the game.

was gunna say I never had such message popup

GOG Galaxy = validation (better twice). And adminrun to both game and Galaxy.
GOG offline = adminrun for installer and game.

Need access to registry. Usually to HKCU section (no admin rights... or maybe depend on exactly OS). Probably CD check is somewhere else.
Also retail version install almost only game exe even for full installation (full also copy HELP folder). If some files are missiong in KAIN\KAIN folder - game ask CD.

everything you said...is not necessary...lol.

I installed verk's full patch and it runs perfectly fine without a retail cd. and I did NOT have to run anything in admin, nor did I have to run galaxy

It is normal to put admin run onto games exe, games config exe (but no map editors\sdk\etc).
It is normal to permanently set adim run onto Galaxy and Steam.
........
Actually, i dont think adminrum is necessary for game itself (for first run) (because it use HKCU\Software and not HKLM\Software to store settings).

But Galaxy is differ thing, just like Steam. Ar first start it configure (depend on install location), put to game folder and execute some files to complete installation - exactly at first run (just like Steam games can be 100% only after first launch)
For subj game it be this file:
http://www.gogdb.org/manifest/6a969a82aa5b1b961f3e7022fb5b7dcb

( http://www.gogdb.org/product/1837805079 )

(gameux is definitely about some Windows services, most likely some from Windows 7 that didnt work\not present on Win8/10, looks like it about Game Explorer)

(Game Explorer service work strange on Windows 7... it removed from Microsoft server (this is why it didnt work properly)... but when there is no connection it know that there is no online, when PC connected to internet it try to connect server...
What is strange here? I have Windows 7 x64 Sp1 Enterprise Edition (not updated since 2014 except very important hotfixes) - and Game Explorer still there, still enabled by default and still well, not fully worked, but it do not cause problems like in Ultimate Edition - common problem with rundll32.exe when games prepare to start for 5 minutes - my EVERY games always start immediately on Win7 Enterprise Edition)

Also, GOG\Galaxy for many games try to enable disabled by default Windows8/10(/11) feature Legacy DirectPlay (should be updated Windows and DirectX 9 to access to this)
https://support.gog.com/hc/en-us/search?&query=directplay

So Galaxy always require admin run for itself (Windows always apply any settings (CPU affinite\priority, adminrun, compatibilities) from parent exe also to all "daughters" process) - to properly intsall games after downloading and validation (always do it after downloading, same as for Steam, every else services, BitTorrent-clients and any apps that have validation feature).
Validate game at least twice. Even for Steam. GOG Galaxy 2.0 lost feature that show you validation result and also it now always redownload exe\config files, DirectX and some else additional redists. It now more important to validate twice.

.......
I didnt buy this game yet, cant say what actually there. For compatibility things GOG\GOG Galaxy use sdb-packages (some sort of executable files, almost like cab-files)(created by very powerful Microsoft Application Compatibility Toolkit (for Win10+ it named Windows ADK)). ini files - obvious - for game settings itself.
I didnt saw mention of reg-files in GOG Galaxy and unofficial GOG Db. I know game that require Win REGISTRY entry to game properly working - Hogs of War (this actually very rare situation when games require installation and not just extracting from install-archives)(GOG game Launchers (e.g. Quake 2) extend that rare list, but it still be very rare and directly by exe - still working as "portable" without installation and admin-run). There is no reg-files, but GOG Galaxy version still put what it need to Registry and HoW working properly.

So... It is first time for me i see that some kind of variable executable file. Cant say what it for (cmd - just like bat file, right? so it should be open by notepad\word\notepad++\ - or at least in HxD that always open anything). But definitely it require admin rights for Galaxy.exe if you install it from Galaxy.
Offline installers always ask admin run, of course.

sdb-packages automatically installed by DISMM Windows service, but there is more ways to manually use it (for unofficial fixes from net it combined with bat-files, but better use Microsoft ACT tool - there is no proper things like this online from other users, for sure) (e.g. for Disciples 2 on Win8/10 there is unofficial bat+sdb that put 100500 options and NO proper one - "dxprimary emulation - disable maxwindowed" (Disciples 2 never be worked properly on Win8/10 without some tweaks, but GOG put own wrapper that fix that un-compatibility)).

This game use that GOG DX DirectDraw wrapper as well. It can be configured (minimum simple settings) - and should be configured - from DXCFG.EXE from game folder.
Also GOG put new GOG DX DirectInput wrapper - but it dont have (yet?) any config tool - settings should be editied directly in dixi.ini file.

Nice. gog can't create the correct nocd-patch by themself while fans did this many years ago. Cool.

actually it isnt gog staff's responsibility to create such things.

technically they are given permission to release all data the devs provide and then to apply as lil changes on their end to make it run and a lot of the times the so called lil changes they are aloud to apply and choose to apply are works from fans.

sad that everyone here doesnt understand that.

you are an idiot if you think its a publishers responsibility to make sure the products they offer run flawlessly on every machine.

goto any other digital store...even steam...and you can easily find that they offer more broken games than gog does in general.

This is literally the only case we've seen of this occurring, and it disappeared after uninstalling and reinstalling the game. My guess is something just went wrong with the initial installation.

Cmon, Wrace! You know what happened here - incomplete installation (now by not matter reason). Seems like OP use GOG Galaxy. You know that this is normal things. It always should be validate after downloading. Again, you know that.
When you blame Square-Enix and GOG(\Steam) for reasons - it ok, i mean you completely right. But now you looks like persons here whining about DRM(-bla-bla) in Hitman - completely unrelated to subj game hating.

Actually it is gog staff's responsibility to create such things because they sell games without DRM, so they need to remove correctly such protection (to create noCD-patch). Sad that everyone here doesnt understand that. :facepalm: You are an idiot if you do not think so. Moreover, on the main pade of BO1 gog wrote that this game was adjusted to work on the newest OS and it does not have DRM. On the Steam only publisher can place games. And publisher share games which were provided for them by gog. Your guess is wrong. It is uncorrect nocd-patch.

If someone who provides games without DRM can't create the correct nocd-patch which was created even by myself (and by Verok too in the case of BO1), it is good reason to laugh on the skill of such bad (gog) programmers.

Moreover, I saw the same situation in another games (which were modified by gog) I checked.