There is a full mission editor: an extremely powerful one. It's called Workbench. In Steam, select "Tools" in your Library instead of "Games" and you'll see the ArmA Reforger Workbench. Install it. It's very impressive, but if you don't have game development experience you're likely to be confused. I was able to figure out how to create an entity and run a script fairly easily, but it's packed with undocumented features we've only just begun exploring. We're hoping documentation will be released soon.
The thing I'm having trouble with is finding out exactly where the engine saves my script files and content in a basic add-on I'm making for educational purposes. I can't seem to find the files anywhere in Windows Explorer. It's not in the ArmA Reforger folder in Documents, and also not in the Enfusion folder in AppData ... the script I've created, as well as all the others, are curiously nowhere to be found ... they work, of course, but it seems to be a complete mystery where they live and that's kind of upsetting 😕
