Hi thor171,
That's really weird! I just installed a clean copy of Ubuntu 18.04.3 on a VM and downloaded the dpkg from here then opened the file (didn't even need to use the Terminal, don't know if that's new) then ran `gb-studio` and it opened as expected. Only things I installed were virtualbox-guest-utils and virtualbox-guest-dkms packages, potentially they could have included some dependencies that made it work :-/
Assuming you followed the instructions at https://www.gbstudio.dev/docs/installation/ the only other thing I could suggest if you're comfortable is installing from source. If you have git, nodejs and yarn installed you can clone the git repository and then install the dependencies by running `yarn` and start the application with `npm start`