My multi-quote functionality seems screwed up at the moment, so:
Savage Worlds: There was a mistake. I called it "Savage Frontiers." The chart is now update. (It is on the far left, 3/4 of the way up.)
Hackmaster: where else would you put it? Maybe if/when I add a bunch of the retro-clones/early edition derivatives. Maybe add a tree from the 1E branch?
What is du/dx = cu + xy? I think you're reading too much into it.

But I'm not going to ruin it by providing my simpler explanation.
FATAL: Better not to spread word of it.
Aberrant: I'm not sure of the popularity. (That's not a slap, just my lack of knowledge.)
Microlite20/E6: Again, if/when I add retro-clones and 0E/BECMI/1E/2E/3E direct derivatives. (Of course, most games are derivatives, but it is a matter of how directly they are derivatives.)
Also remember that with all of these there is a space factor. (To a degree, it is digital after all.) Anyway, the point is I'm trying to focus on games that have a certain amount of popularity, or are groundbreaking in some way or represent a niche that isn't otherwise filled.