• Removal of SVG files, .translation, and imports. I am not sure what was causing these files to have incorrect imports, but when I opened the project in godot I had ~50 import errors. Regardless of what I did to fix the error message, the only improvement was deletion of the .import files, which forced godot to regenerate the import files, but then everything had default import settings anyway, and it added lots of code to review. My best guess is that the imports were used previously, but at some point textures were generated from them, and thus the SVG files never got used. Maybe during the migration this data got lost, and godot was unable to properly handle them, but the texture files did get migrated and work properly. As for the translation files, I don't think they were used anywhere, and one was incorrectly named? I would love to readd the files later on, but for now they are at least kept in the git history.

• OS.get_name() now returns Linux instead of X11, not sure about every possible use case, and I believe godot 4 started offering a DisplayServer for handling that. So to avoid any larger changes I have simply duplicated the functionality, and it will be removed later.

• Default icon fix, the set_icon function doesn't exist in godot 4, and the intended way to set the icon is through project settings instead. However, only PNGs are accepted, so I exported the SVG as PNG with Gimp.

• center_window doesn't exist in godot 4 and there is no replacement AFAIK, so I removed it. For now I don't think it is an issue that the first time you run catapult you won't have the window centered, as I will have to look at the implementation of the center_window and then reimplement it myself. Should be simple, but again more code for review than is necessary.

• I am not sure why @qrrk didn't consider Handling of multiple game installations point finished, as I was able to run multiple experimental CDDA versions just fine. However, I did notice that you are not able to run older versions if you run the newer versions. After some debugging, I found the following error from the CDDA itself.

Error while initializing the interface:
loading font settings from /home/XXX/godot/dda/userdata/config/fonts.json failed:
Json error:
home/XXX/godot/dda/userdata/config/fonts.json:3:16: <color_white><color_cyan>Expected string</color>

{
  "//": "See docs/user-guides/FONT_OPTIONS.md for an explanation of this file.",
<color_light_red>  "typeface": [ { "path": "data/font/Terminus.ttf", "hinting": "Bitmap" }, { "path": "data/font/unifont.ttf", "hinting": "Default" } ],</color>
              <color_cyan>▲▲▲</color>
  "gui_typeface": [ { "path": "data/font/Roboto-Medium.ttf", "hinting": "Light" }, { "path": "data/font/Terminus.ttf", "hinting": "Bitmap" }, { "path": "data/font/unifont.ttf", "hinting": "Default" } ],
  "map_typeface": [ { "path": "data/font/Terminus.ttf", "hinting": "Bitmap" }, { "path": "data/font/unifont.ttf", "hinting": "Default" } ],
</color>

I believe it is caused by CleverRaven/Cataclysm-DDA#78830 as they changed the font config expectations(?) and they allowed the migration from old to new, but not from new to old. This means if you run experimental, and then want to use stable, catapult will just hang for a second and then silently crash. Unfortunately, we are not checking the exit code right now, nor the stderr output. I don't think this is an issue with the migration though as this doesn't work even in godot 3 version. I am pretty sure we can fix it somehow eventually.