A few years ago I started experimenting with an old GEOS 128 ROM image available on the internet, with the idea of installing it permanently into my C128. After trying it out on Vice, I was quite disappointed. Not only was it slow to decompress in memory, but filled the screen with garbage and didn't handle the 40/80-column key properly. The main problem seemed to be it was based on a memory dump which carried lots of garbage. So I set about creating a new ROM image from my original disks.
Then I had to change houses and the project remained frozen for a while. Last year I came across my working files and decided to go back to the drawing board, but after toying around with many ideas, I came to the conclusion it would be nearly impossible to do a one-size-fits-all ROM, and so GEOS Kernal Construction Set was born. It allows you to build a customized GEOS 128 2.0 kernal, with your very own serial number, and specify which drive type and device number it will boot auto-execs and the deskTop from.
Additionally, you can choose a different default input driver (currently 1351 mouse, standard and accelerated), and support for either Commodore 17xx REUs or GEORAM (and compatible) memory expansions. The first public version has been up since January 2022 at peeknpoke.com.ar/gkcs, and today I have added the German-language editions, which led me to introduce the tool in this forum.
Feel free to experiment but keep in mind it's still under development, so there are still some rough edges. Comments and suggestions are certainly welcome!