I realized fairly quickly that I should probably have the layout of the game's levels planned ahead of time, since I'm going to allow backtracking and such, since I'm going to allow backtracking.
Since I don't have a level-up system, it wouldn't be beneficial to the player to have to backtrack potentially dangerous areas over and over, so I decided I want to have shortcuts that allow you to go back quicker, which means my typical "make it up as I go" level design style won't work, here. I wish I could show screenshots of the game's map as I work on it, but I don't want to spoil things.
I also have room-shape presets I've created. No real point in showing those off, though, so you'll just have to trust that I'm working on something that will speed up the completion of the game by quite a bit.