Welcome to the Glypha III wiki!
I think we can all guess the inspiration for Glypha. For me, Glypha has always been a test of sorts. When I first wrote it, it was to see if I could reproduce an arcade game I was a fan of — with my own touches, I suppose. Later when I switched from Pascal to C, Glypha was the first port — a test of my ability to program in C. Later, when asked to make a commercial version of Glider, in color, I again returned to Glypha and rewrote it to support color Macintoshs. Again, a test bed.
I worked at a pizza place for a year when I was younger. They had a Joust machine in the restaurant. I loved playing that game. When I wrote Glypha I hadn't played Joust in probably four or five years. After Glypha though I had a chance to play Joust again and I was suprised at how "sluggish" it seemed. I don't know, I sort of prefer the dynamics of Glypha. It feels a little snappier.
Since the sources for Glypha have been available for some time, a few years back someone ported it to the iPhone, FWIW.