The sky was always a gradient, it's just upside-down and higher-contrast now. One of those things was on purpose. (On a possibly unrelated note: guess I shouldn't use green and red as distinct global colors, for the sake of colorblindness.) Tile graphics are likely to get another overhaul before any sort of proper release.
The level's the same, it just has a roof. I added ceilings for performance. It limits draw distance. This was a terrible idea for about three weeks, but now I'm pretty sure it's faster overall. Where it's not, well, I need better levels. That's why the editor is different. Right now I'm trying to compress savegames to where I can call them "passwords" with a straight face. Then people can share levels.
There's mild complexity in how ceilings work, where floors are allowed to stick through them. That's probably less confusing than where red walls also have red ceilings, because again, I do need to make better levels.
Enemies are animated now! Which admittedly looks so-so at current speeds. They're timed with the global vblank counter, which naively cycles every four seconds, so at some point I'll add another byte that only increments every fourth vblank or something. That should make the various bouncing and shifting look much better. Crank the overclocking in Mesen for an idea of what they're supposed to be doing.
But the blue guys do emerge from the floor when you first look at them. That was weirdly easy to implement. Kind of a zombie gimmick, applied to them for now because they're the right height for it. There will eventually be more enemy types, if only because an "invisible" spectre-style monster would also be weirdly easy to implement. It'll change the palette.