Instructions to set up and run Vassal on linux

Java 11 is rather old. Perhaps you can upgrade it to a more recent version - say 20 or newer. To do that, open a terminal and type

$ sudo apt update
$ sudo apt upgrade 

Sounds like you are not in the directory where you downloaded the file. The message

Cannot open: No such file or directory exists

means that the file you are trying to extract isn’t where you expect it to be.

In a terminal, do

$ ls

to see what files are in the current directory. Typically your terminal starts in your home directory ~/, while your downloads typically go in ~/Downloads. Perhaps you simply need to change directory to ~/Downloads:

$ cd Downloads
$ ls 

You should see the file

VASSAL-3.7.16-linux.tar.bz2

if that’s were you downloaded the installation. Once you have located the file, you can unpack it

$ tar -xjf VASSAL-3.7.16-linux.tar.bz2

This will unpack the archive in the current directory. If you want the installation to go elsewhere, say /opt, then you can do

$ tar -xjf VASSAL-3.7.16-linux.tar.bz2 -C /opt

Alternatively, you can open your file manager (I believe Pop_OS! uses GNOME for its desktop, which means your file manager is nautilus) and find the file VASSAL-3.7.16-linux.tar.bz2 and double-click it to open in your archive manager (File-roller in GNOME) and use that graphical user interface (GUI) to extract the the archive to where you want it.

You need to unpack the archive before anything works. For example, the post How to Integrate VASSAL into the Linux Desktop assumes you already have unpacked the installation.

Suppose you have unpacked VASSAL into /opt/vassal, then you can downloaded integration.sh (remember that it will typically end up in ~/Downloads), and move that to /opt/vassal

$ mv ~/Downloads/integration.sh /opt/vassal 
$ cd /opt/vassal 
$ sh integration.sh

to set-up the mime-types for desktop integration. But, you need VASSAL unpacked first.

Hope this helps.

Yours,
Christian