Hello! I will speak from an enthusiastic group of people playing Submarine Titans together. There is almost 100 of us, we like the game and dream about how could Subtitans 2 look like.
When we started this group and started playing we noticed few bugs and balance problems we wanted to solve. I started looking into this and after a few weeks of studying I was able to make first “patch” using Cheat Engine trainer. Before that I used disassembly programm to examine raw game code and spent a lot of time in this process. This approach helped me to fix few dozens of issuies and make numerous improvements which we all wanted. After 4 months of development I made almost 400 changes.
Yet there are things that are too intricate to implement with this approach, like, for example, an orders queue, like in most RTS games. Submarine Titans is a complex game with a lot of different game mechanics and is very APM requiring, so queuing orders is a very wanted thing. Another thing is game crash with “Internal Error” message that happens randomly every second game and is really frustrating and we can’t track down the cause. There are few dozens more things we have figured out that we want to change to improve game experience.
Having a source code would make many things possible to make, which now are not. Please, if you have it or know who does, share it with me on terms of non-commertial use and non-distribution, of course.
From fans of the game, with much hope.

We on youtube https://www.youtube.com/@Artyom1Aws/videos
We on discord - https://discord.gg/gT5AZYmrjY

FYI, Ellipse Studios closed shortly after Submarine Titans shipped.

Someone periodically releases fixes

That was GOG updating their DirectDraw wrapper for old games, nothing to do with the game code but the way the ancient graphics system interfaces with DirectX.

Сopyright owners began selling game on Steam and GOG platforms. This means that they have the source code, because it is given to the owners of the game.

You'd be surprised at how many games are sold with their source codes lost. It's not necessary for a game to be recompiled just to get it on a storefront.

Either way, publishers seldom read GOG forums. Ping Strategy First directly instead: http://www.strategyfirst.com/contact-us/

Oк. Let's hope that they will respond, although the chances are very small. We really want to make the game better than it is now.