Thanks. Actually an more than half a year old experiment. Just before starting the Nonogram.
I was about to bring order in all of these program statements, put them into data statements, and guess it would be more compressed over all. Coming back to it by accident, I still love the graphic effect - knowing it's tms9918 compatible - and when was this chip released/introduced/manufactured ? 1979 or earlier ?
This looks like a board, but maybe it could be platforms, maybe something to jump around on, different height, levels or something. And as you say, sprites are available to put on top.
I'm starting to think of this TI thinking, graphics and programming as therapy. Relaxing and having a bit of fun.