This is not going as well as planned. I’ve spent the first few hours writing a working PPU emulator, and up until now mostly writing high level utility code to make the PPU easier to work with. I also finished the landscape generator, it still needs to put foliage and stuff there, but that shouldn’t be all that painful! Have an unimpressive screenshot of it:

Can't really make much of it, but I promise it's generated a landscape.