Download my fixed executables here:
https://www.nexusmods.com/imperialglory/mods/2

or here:
.com/file/fgg2dcq3mxhkz79/imperial_glory_fixed_resolutions.7z/file
(Add mediafire in front of this link. Steam blocks their links for w/e reason.)

Installation:
Download the archive. Unzip the archive and copy the exe corresponding to the resolution you wish to use and paste it to the game's install directory and overwrite the original.

For instance, for 2k resolution = unzip the archive and open the folder named 2560x1440 and right-click on and copy the ImperialGlory.exe and paste it to
C:\Program Files (x86)\Steam\steamapps\common\Imperial Glory
and agree to overwrite the original when prompted.

Once that's done, start the game; the new resolution will be the only one available in the menu options. Select it and restart the game for it to take effect.

The next two steps are completely optional but I'd also recommend opening Config.sb in your Imperial Glory folder with notepad and changing FULLSCREEN to FALSE as this will force the game to start in windowed mode and avoids crashes when using Alt+TAB. Afterwards, if you want to get rid of the window's border, you can download Borderless Gaming and add Imperial Glory's process to the app and it'll automatically switch the game's normal window into a borderless window whenever you run the game, as long as the Borderless Gaming app is running in the background.

Borderless Gaming on Github:
https://github.com/Codeusa/Borderless-Gaming/releases

If want to use a different resolution than the ones provided in the fixed executables, you can follow this guide to add a custom resolution.

First download a hex editor. HxD is the one I use. You can get it here:
https://mh-nexus.de/en/hxd/

You'll need to convert your desired resolution into hex values. Widescreen game forums has a good resolution-to-hex chart which you can find here:
https://www.wsgf.org/article/common-hex-values

If you have a custom resolution that's uncommon, there are hex converters online you could use to calculate it -- The one on rapidtables is clean and simple to use(hint, switch conversion type to decimal-to-hexadecimal, and remember little endian data output is the one used here.)
https://www.rapidtables.com/convert/number/decimal-to-hex.html

Now the next step is to open imperialglory.exe in your hex editor of choice and search for the hex strings for each resolution shown below and replace the hex values with the ones for your desired resolution. Remember, you have to replace ALL four default resolutions with the one you want to avoid the resolution resetting on restarts.

How to do this in HxD; open imperialglory.exe in HxD, click Search > Find > switch to Hex-values tab then copy/paste the hex strings below. Then click Ok; it'll take you straight to it and the whole string will be highlighted. You'll then change the appropriate hex values -- in the 800x600 example below, for 1920x1080 just click in front of '20' and type out 8007, and click in front of the '58' and type 3804 -- HxD will automatically add spaces as needed. Just search for the hex strings and replace the numbers as shown below.

**The hex values or strings(w/e you like) you'll be searching for are located very close to each other; literally back-to-back starting with the first one for 800x600...**

(800x600)
Search for hex string - 20 03 00 00 58 02 00 00
For 1920x1080 - Replace 20 03 with 80 07 and replace 58 02 with 38 04
For 2560x1440 - Replace 20 03 with 00 0A and replace 58 02 with A0 05
For 3840x2160 - Replace 20 03 with 00 0F and replace 58 02 with 70 08

(1024x768)
Search for hex string - 00 04 00 00 00 03 00 00
For 1920x1080 - Replace 00 04 with 80 07 and replace 00 03 with 38 04
For 2560x1440 - Replace 00 04 with 00 0A and replace 00 03 with A0 05
For 3840x2160 - Replace 00 04 with 00 0F and replace 00 03 with 70 08

(1152x864)
Search for hex string - 80 04 00 00 60 03 00 00
For 1920x1080 - Replace 80 04 with 80 07 and replace 60 03 with 38 04
For 2560x1440 - Replace 80 04 with 00 0A and replace 60 03 with A0 05
For 3840x2160 - Replace 80 04 with 00 0F and replace 60 03 with 70 08

(1280x1024)
Search for hex string - 00 05 00 00 00 04 00 00
For 1920x1080 - Replace 00 05 with 80 07 and replace 00 04 with 38 04
For 2560x1440 - Replace 00 05 with 00 0A and replace 00 04 with A0 05
For 3840x2160 - Replace 00 05 with 00 0F and replace 00 04 with 70 08

Once you change all four resolutions to your desired one, save it(Ctrl+S), close HxD and start the game; the new resolution will be the only one available in the menu options. Select it and restart the game for it to take effect.