+1 to @kdrnic for the outstanding Plan Of Action, I like it.
I’d briefly like to mention a few of the map editors available. Don’t take my opinions as canon, I am sure there are many others and I’d also like to hear your recommendations 🙂
I mainly use “Eureka”, a cross-platform map editor. As much as I love it, there are some caveats: not being as prolific as some of the more popular editors, searching for tutorials and help online can take some digging. Also the latest v2 release has some instability issues, I suggest sticking to v1.27b
The more popular editor is called “Doom Builder”, and was also used by Romero when he created his Sigil episode in 2019. This editor has more tutorials, videos etc online, and would likely be a better candidate for new mappers. There are a bunch of video tutorials on its website.
I am going to use Doom Builder for this project as I’ve always wanted to try it.
https://www.doombuilder.com/
https://eureka-editor.sourceforge.net/