It would appear, "libcurl3" was tossed away and GOG needs to update its system requirements.
But, I believe, this is a "red herring". Because I've seen some familiar issue down in your post.

start.sh is not the game's executable. It is the very same GOG's wrapper I've mentioned in my previous post. Technically, it is a "Shell Script" -- text file containing instructions (setting variables, preloading libraries, executing "launchers" etc.). Sometimes GOG tries to be "clever" with it and likes to substitute system libraries with its own, bundled with a game, and said libraries may be incompatible with other (system, this time) libraries, thus ruining everything. That's why it is usually better to circumvent GOG's "start.sh" script and launch a game directly.
Oh, and BTW, the "*.desktop" files are just like "lables" in Windows ("*.lnk"), only in Linux they are more useful, as Linux executables do not (and can not -- that is intentioal) have embedded icons in them, so these "*.desktop" files provide nicely looking link to place on a desktop (there is more to it, but that's besides the point).

But yet again, another false lead.

Now, that's the deal!
A well known issue OpenSSL version 1.0 was discontinued not that long ago and was thrown out from Ubuntu (from 19.10 onward). It was discarded in Fedora even earlier, that's why I've dealt with this issue a lot of times. For some strange reason games (or rather, game engines), even single-player "DRM-free" ones have the need of network cryprography. :(
But on to the point, two files are needed: "libssl.so.1.0.0" and "libcrypto.so.1.0.0" (32bit versions in our case, but I've encountered games requiring 64bit versions as well, so while we are at it, it is probably a good idea to grab both).
Unfortunately, as I said, OpenSSL 1.0 was tossed, so no, you can not install these libraries the normal way (via packet manager), and no, "libssl1.1" will not do.

Strange fact is that your supposed GOG version tries to search for the libraries in your Steam installation directory. It fails most probably due to "Steam Runtime" not been installed. :)

You can download these libraries manually (from "Ubuntu 18.04") and shove them to the game.

Here are the links:
http://archive.ubuntu.com/ubuntu/pool/main/o/openssl1.0/libssl1.0.0_1.0.2n-1ubuntu5.3_i386.deb
http://archive.ubuntu.com/ubuntu/pool/main/o/openssl1.0/libssl1.0.0_1.0.2n-1ubuntu5.3_amd64.deb

It would probably not be a good idea to install these packages system-wide. Just extract needed libraries and copy them into game "lib" directory (if there is one, otherwise you should create it) and ensure the game finds them (use LD_LIBRARY_PATH or LD_PRELOAD environment variables or some other, more convoluted way, like writing [url=https://en.wikipedia.org/wiki/Rpath_(linking)] RPATH[/url] into the game's executable).

Again Alm888 Thank you for taking the time to trouble shoot this with me. I think I have taken up enough of your time, I am going to try and learn about how to do what you suggested.

As for GOG, or Monolith devs, I feel like this could be something fixed on their end to help make installing their game an easier process. I recently installed a linux distro knowing its downsides fully well, especially when it comes to getting some games to run so that's on me. I am glad they have the linux files at all and not just a windows installer only.

Again Alm888 thanks again for taking time out of your day to help out some rando linux noob.

For at least one game that requires libssl1.0 (Undertale in this case), you might try running the Windows version via WINE, as that can be easier than trying to install an obsolete (and likely insecure) library that, for whatever reason, the game requires.

Believe me, there are more games, way too more. This way one can just ditch half of the GOG's library and just use Windows versions in WINE.
Supplying libraries to a game is not that hard. One just needs to create a launch script (if GOG does, why the heck we can not do he same?!) "launch_game.sh" (or whatever) containing just this: Of course, the <game_executable_name> thing should be replaced with an actual game executable.

Is Desperados III for Linux coming to GOG?

I hope so, I'm almost done moving over to Linux so more native support is always welcome.

Having trouble with Parkitect (native) on my laptop. DRI_PRIME is not working and always loads with the integrated card instead of the discrete one.
Have tried running the start.sh that the gog installer makes and the Parkitect.x86_64 executable directly. It's the only game I have that doesn't work as intended. Also tried passing MESA_VK_DEVICE_SELECT instead, also didn't work
Anyone ever had any similar issues? what should I try.
This on the latest version of the game, 1.6

I’m waiting for it too ;)

Seeing that their previous game is here with its Linux version, and the Linux version of Desperados Ⅲ is already available on Steam, it would be surprising to learn it is actually not going to be distributed through GOG too. Surprising and highly disappointing, as I really want to play it.

Is Star Renegades going to have a Linux build? I remember seeing a Linux icon when they added the game page, but now is gone.

Found this thread in the Steam forums

https://steamcommunity.com/app/651670/discussions/0/2792746481287636681/

Looks like it was planned but then dropped though they haven't ruled out a native port coming post launch.

Of course, God forbid I get hyped for something, oh well, thanks for the info.

Looks like THQ Nordic decided to give GOG Linux users the short end of the stick with Desperados III. We aren't getting the game. Someone quoting their response from Discord:

I'll be honest, I'm surprised. I understand some Linux games do take time to get here and it's fine in my book, but the publisher withholding it is totally bollocks.

It's kinda stupid to spend time and resources porting the game to 2 other platforms but releasing them only on 1 store.

Agreed, and especially since both THQ Nordic and Mimi didn't have problems releasing their games on GOG in the past.

In case you want to extract Konami's Collector's bundle, I made a helper script.