Arright. I only mentioned Beach and Volcano, which I think are definitely happening, but I am so sold for 5 new themes, which would make the grid 5x3 instead of 5x2.
Beach: Covered
Volcano: Covered
Mountain: Not unlikely. Home to the fuzzies and tight platforminf stages. A nighttime theme could even have no-backwards-scrolling, where you can only go forward and never go back, because the screen stops you from moving. However, the screen doesn’t move unless you do. I’m shocked that a form of no-backwards-scrolling hasn’t been implemented into the auto-scrolling menu, but ah well.
Fortress / Tower: This is for all of your dungeon levels that don’t really fit the lava aesthetic, but DO fit the spikes balls, snake block paths, and the hopes and dreams of those who wanted to place an Amp. For everybody else, it’s just your typical fortress theme from the New Soup games. A nighttime theme could be looping walls. On a vertical level, you travel from the right wall to the left wall. On a horizontal level, falling into a pit sends you to the top of the screen, always. This is definitely the jankiest of nighttime themes, and will probably need to undergo several modifications so that cheese doesn’t become the norm.
Space?: A mode where you can swim in the sky during the day? An alternative to the Underwater theme for a map where you can have free reign? I guess... but I mean... it hasn’t been used since Super Mario Land 2. For a nighttime theme, I’d say give all of the enemies their nighttime ground behaviors, and just throw them in a swimming environment, and watch magic happen.