Nope, I'm getting
honeycomb@bratek:~/robinson-linux-x64-2018.12.08-21.11.52-a7fdcf0$ ./robinson.jar ./robinson.jar: line 1: syntax error near unexpected token `)'
./robinson.jar: line 1: `:;exec $dirname $0)/bin/java -Xdebug -XX:-OmitStackTraceInFastThrow -XX:MaxGCPauseMillis=20 -Dhttps.protocols=TLSv1 -Drobinson.version=0.0.1-SNAPSHOT -jar $0 "$@"'
I was being silly with the permissions of the gaming user: it was enough to add him to the 'video' group and now I get "frames 29", though total CPU usage when the game is idle is still quite high: 70%. Anyway, I don't need to to move to Windows, which is a happy turn of events. :)