Purely scratch padding ideas here. However, for me its a good day when things work as expected.
I did put up players on the screen. I did use them to mask. Which means I will have added colors on my screen, going way beyond the original.

Also, I finally tested out that idea I had for constantly polling the joystick and immediately responding to any valid change without regard to the animation cadence, and it works great! In assembler.

I say, because I got so excited about it, I back ported it to the original Nerm in basic, and there Basic is so slow it just is so disappointing and so I went down the avenue for no particular reason, wasting a bunch of time.
Still, I was making so much progress, I should call it a good day anyway.

These early previews are ugly, because I don't have the players tracking the snake head, so it appears cut off right now. And I've clearly just put a white player on the screen to test masking. And...but you know, the joystick control is gonna be sweet. And that's today's takeaway.