Glad to hear people are getting started! I've got a couple of things to say about modding:
1. If your mod crashes without any good error message, I'm eager to sort things out! My big mistake with Notrium was that it didn't have any/good error messages. Just send me your crashing mod, I'll run it here and add an error message to the game, along with telling you what's wrong.
2. I'll do what I can to ease modding now, but most of the major things will have to wait until the main game is a bit farther. That means the editor may lack some features, but I'm hoping we can make do with it.
3. The starting map is specified in the script/settings.ini.
4. Backups are your friend. And what's more, the editor makes a backup of your map each time you save it! You'll need to delete the old ones sometimes, when they start taking up gigabytes.
5. As I add more features to the game, I'm determined to tell you what changes the script/*.ini files need. I might forget this sometimes, so just tell me when that happens. My plan is to not break any mods you're working on now, so let's hope I can stick to it.
6. I'll be making a barebones mod at some point myself, if somebody else doesn't beat me to it. Basically you can dump all of the maps, sounds and graphics. The game will need the gui, mainmap, and script folders. At the moment I think it'll also need some secret files from the sounds and graphics folders, of which I'm not aware.