When I started to use Zorin for the first time last year, I was able to download the official VICE emulator, eDuke32, and Snes9x from the Software Center, but after certain events required me to do a re-install, these packages are not available anymore. I have no idea why. I can still install VICE, but it is not the latest version and it goes by the name of vice-jz and vice-pasman.
How were those app's originally installed from Software store, e.g. apt, Flatpak, Snap source?
It is a daily routine that Gnome Software Center does not work properly. I feel like charging Gnome for the cost to the user community.
I looked and those packages are not available on my Gnome Software either.
However, I also do not use flatpak or Snap - so I remove both (and their plugins). This will cause Flatpak or Snap only packages to not appear in Software Store.
You may be missing flatpak and are also not seeing flatpak packages offered. In a web search on installing those three on Ubuntu - I noticed that all were pushing to be installed as Flatpak instead of using the standard official APT. Just another case of Developers using force to bend users to their will.
You could install Flatpak or ensure that it is installed.
Install those packages as .deb packages. For example:
Thank you, now VICE and eDuke32 now appear in the GSS.
I can understand why you don't use Flatpaks. Maybe they are deemed a security risk, but for me (at least on my system), I click install on these Flatpaks and it says "Installing 0%" but nothing happens for ages.
Can you try running
Then see if they install?