GEOS was developed by Berkeley Softworks, and its founder Brian Dougherty is giving a rare interview on Zoom. The free conference takes place on Thursday, April 18, 2024 at 7:30PM ET (Toronto, Canada).
If you're attending, the Zoom details are here: https://www.tpug.ca
A 32MB ProDOS image of GEOS is one of the things that I use for testing Apple Mouse cards (and A2USB or A2VGA cards in Mouse mode). It essentially requires the Mouse not only for input but also as a programmable interrupt generator to be able to do multi tasking on an Apple II which otherwise really isn't possible because the Apple II doesn't have a way to generate interrupts on its own. Some other cards like clock cards also provide programmable interrupts but not the "no slot" type clocks.
Anyway, the GEOS environment was also known for their office suite GEO Works. And it was cross platform as there was GEOS for the C64 and IBM PC also. It was something that was kind of way ahead of its time in some ways although of course it was also obviously inspired by the Mac and other GUI products of the day too.