I always heard that the Appleseed manga was actually much more popular in the US than Japan at the time. It was one of the first Japan comics I can recall from my time on the comic scene, from eclipse with studio proteus doing the flip and translation. Blew most everything I had seen from US comics out of the water.
I did hear he wasn’t thrilled with some translation stuff but nothing about why he quit making awesome comics altogether. Every once in a while I look for interviews with Shirow, and have heard all sorts of stuff. If you squint you can have the appleseed world being later in the timeline of the GitS world.
Freegards
Pretty much. I always kinda thought of it like that. All his productions I’m aware of are pretty closely related. If not the same time/reality, at least an alternate one. The one with the 4 girls in/with mech armor (the name escapes me) is in the Dominion Tank Police world IIRC and that could easily be in a corner of GITS somewhere. Appleseed, if you pretend that everything but the city is blasted earth, could be the result of the war prior to GITS. It could even be rationalized that since the city is cut off from the planet pretty much, it is in that world and the general population there only think the planet is blasted.
The tech is the same. the huge sentry robots from the movies are really just scaled up Tachikomas without AI. He seems to have had intentions at a much bigger shared (in some form) universe for his properties than ever got actualized IMO.