So I spent all night last night trying to get the fading to black code someone sent me actually working using C. I went to sleep at 3am despite having still failed at it. I woke up at 2pm today. After taking my pills and my daily m&ms bag (I need to eat something after taking my pills so my throat goes back to normal. Don't ask why.) I went back to work.
After an hour, I FINALLY got the stupid thing working. Now when you exit a screen, the screen fades to black quickly and the next screen pops up. Why did I do this? To avoid the flashing of the background displaying wrong 8x8 tiles. I think this is a good solution to it.
I played a little of it last night and made a YouTube video of it. It was during the editing that I noticed I had weirdly made the title screen colors incorrect. I fixed this now. After I put the YouTube video up. And the YouTube video doesn't have the fading, either since I just now finished it.
I tried it without sound. I tried it on my GBC just now and realized the music stalls while the fading occurs. So I kept wondering why my work around wasn't working, until I realized I never set the level number to 1! So now level=1 and all is well, until I run into another problem...