For versions of Ubuntu past 16.04. 16.04 users can completely disregard this and get on with it.
What the hell is ZSNES?
ZSNES is an emulator for personal computers to play images of Super Nintendo / Nintendo Super Family Computer (Famicom) games. The Super Nintendo has a shedload of awesome video games which were made from the very beginning of its life, all the way to its retail end-of-life, and being a prime example of retro gaming's "Glory days" for the 16-bit generation it had garnered enough love and appreciation that some dedicated programmers made an emulator for it with the purpose of playing as many games from the system as possible on personal computers, and to have the experience be shared with others through local or network multiplayer via the emulator.
The legality of playing console games on PC is often in contention; this is a legal grey-area which can yield legal trouble for end-users who are not careful with their downloading habits. Due to this, resources for game images will remain unavailable in this guide but there's enough information on the Internet about this where my assistance isn't necessary.
But I can install it from the Ubuntu repo already!
1.51 has the netplay functionality disabled, sadly which means the only other reasonable alternative would be to install SNES9k, a version of SNES9x with Kaillera netplay built-in but that appears to be only for Windows. Unless you feel like installing wine just to play SNES games with people around the world, older versions of zsnes is the only way to go about it.
Until the ZSNES team gain enough motivation to release ZSNES 1.52 and make it accessible from their website, this is the best we have. If you don't care about netplay, go ahead and install 1.51 from the Ubuntu repo
Installation (past 16.04)
If you're on Ubuntu 16.04, the 1.42 package is already available; just do
sudo apt-get install zsnesand be done.
Stuff to get beforehand
Because ZSNES 1.42 relied on some older libraries than what your version of Ubuntu may have, you might want to fetch libpng12-0:i386 beforehand. It can bbe found here; Ubuntu – Error
Getting the emulator
Due to time taking its toll on availability, ZSNES 1.42 can no longer be found in conventional download mirrors for Ubuntu (though 1.36 exists for some reason). Because of this, I decided an alternative link that may exist after the original one becomes unavailable might be beneficial to supply.
ZSNES 1.42 can be had from the following download mirrors;
Direct mirror 1: http://ftp.iinet.net.au/pub/ubuntu-archive/pool/multiverse/z/zsnes/zsnes_1.420-2ubuntu1_i386.deb
Direct mirror 2: http://pc.cd/63
After downloading the package, it's simply a matter of configuring the emulator to use your preferred controls, fetching whatever base carts are necessary for some games and making your friends use ZSNES 1.42 for the sake of netplay with whatever games are agreed upon.
Bonus brownies
Old video games wouldn't be the same without their bonuses, yeah? If you can convince all of your friends to use the same file sharing service on their desktops, there is a possibility everyone who you convinced to install ZSNES can also supply their own ROM files you'll receive when your service syncs directories. There use to be services like Zbattle and there is Z-Net, but these things are exclusive to Microsoft Windows and the latter doesn't even exist anymore, so wish you luck getting these to work in Linux.
