Yesterday and today I was having so much trouble with the game and bugs kept popping up everywhere that I had it. I deleted all the in-game code and started over again. This time I tried to keep things very simple. And you know what? I think it worked. I haven't had any problems (well, except for the triangle noise being too loud, but I don't know how to fix that. And why call it a triangle noise? A triangle goes "ting!" when you strike it, but the triangle sounds like when you pause in Super Mario Bros. 2, that kind of bass.)
Anyway, I wanted something fairly simple to design. So I designed a cave level. I'm still using only one sprite .chr file. I figure that may change since I want to put in as many levels as I possibly can into my 32K cartridge (so no mappers, especially for a first project.)
This went through a few tries before I found a design where it worked. I found my collection of all the black Tengen NES cartridges and then some.