I managed to get it to work in full screen mode. Here's what I did:
1. go into properties for "Launch STAR WARS® - Rebellion.lnk"
2. Go to the Shortcut Tab and add -w at the end of the Target field. It should look something like "D:\GOG Galaxy\Games\Star Wars - Rebellion\REBEXE.EXE" -w
That's how it is for me because that's where I have the game installed.
3. click apply and then click ok.
4. Go to properties on REBEXE.exe
5. go to the "compatibility" tab
6. click on "Change Settings for All Users"
7. I put a check on "Run this program in compatibility mode for" and I selected Windows 8.
8. Put a check on "Run in 640x480 screen resolution".
9. Put a check on "Run this program as an administrator"
10. apply and ok.

Now run the game using the "Launch STAR WARS® - Rebellion.lnk" shortcut.

It works fine for me now in full screen.

I tried all that and it opens in the correct resolution fullscreen but it does so as a Window on a desktop meaning the bottom is cut off as the window title bar is at the top...

I'm not sure what could be causing that. The best I can recommend is play around with more settings in the shortcut or exe properties and see if you can find something that works. Or maybe check your video card settings? Sorry, I wish I could be of more assistance.

Why does the game launch in a small window on the top left corner? How can I maximize it get it fullscreen or resize the window?

I don't know why it happens but if you look up this page, we are discussing it and I put steps down for how I was able to fix it on my computer. I hope it helps.

I got mine to work fullscreen by doing the following:

1) Uninstall GoG-copy via the Manage Installation
2) Download the stand alone installer
3) Ran installer but, installed it outside of the GoG directories, I picked my users folder in C:\Users\
4) Launched the game and it ran in normal full screen no probs

I have unticked the Auto-updates as I don't want this faff again.

Is there a way to play with this patch but without the post 1990s ship changes (IE keeping the carrack light cruiser)?

It doesn't need the stand alone installer. I uninstalled my installed version through the app, installed the game again and now it runs properly in full screen. (Win11, 4K monitor, RX7900 XTX)

I cannot get this to start fullscreen, i have 5 monitors and I cant adjust resolution to play a game without fucking all my screens up.

Tried uninstalling and reinstalling, uninstalling and reinstalling into new directory, -w which does window but no option to maximize, what else is there?

win 11, rx3090

Updated to manage GoG 1.0 v4 version of the game (though tactical battle rendering isn't as nice).

Finally released all capital ships sprites.

Feedbacks are welcome.