@ Uberdude:
Yes, OGS works fine, thanks!
I neither have the Java browser plugin (only supported for IE11, afaik) nor a working Java environment on my laptop
@ Tryss:
I've sent you a PM today as not to turn this thread into a Linux forum.
I get a fatal error, which, as I've found out after sending you the PM, seems to be inherent in (and reproducible with) OpenJDK.
They suggested Oracle JDK, which I downloaded in V12 and V8, but the installation instructions I followed failed ("path-alternatives" were accepted in bash, only the system default Java stayed OpenJDK9, so, no change).
Since all installations instruction copy the JDK files into different system folders, I got afraid of ruining my system and gave up!
I'll be fine with OGS and IGS, at this moment more than I can chew.
I'm drowning in tsumegos and possibilities to play AIs, so no hurry with KGS.