Mame is a Multiple arcade machine emulator allowing computers to play games from arcade machines by providing it with rom files. Installation is straight forward but can have some pitfalls if you don't know the procedure.
Installing Mame is as easy as opening Appgrid or Ubuntu software centre, searching for it and choosing install. Once it's finished installing, it can be launched using it's icon in your applications/games menu or by typing "mame" into a terminal. Just like the Amiga emulator, it needs opening to do a first initialisation and might give some errors. Close it down again and most of the bits it needed to configure should have been done.
Many people struggle with where to put game roms, mame's configuration automatically searches several locations. The most obvious location it searches is in your home folder ~/mame/roms but for some reason, mame doesn't make this so a folder named "mame" needs to be created in the home directory. Once created that one needs opening and then another folder named "roms" needs creating. This is where game roms need to be placed.
There are other locations to store them or you can even add your own by modifying mame's configuration file. Opening the home folder and showing hidden files lets it be accessed at ~/.mame/mame.ini
If any changes made in the mame.ini file prevents mame from working, just run mame -cc in a terminal to reset it back to defaults.
A google search shows many places to download roms, but again, in order to legally use them, you need to own the physical game or have purchased a license. For more see http://wiki.mamedev.org/index.php/FAQ:ROMs#How_do_I_legally_obtain_ROMs_or_disk_images_to_run_on_MAME.3F Rom files can be left as .zip files and placed directly into the roms directory like that, mame automatically unzips files as it needs them.
Many games seem to work very well with Gizmo, but struggles with newer graphic intensive games. High end gaming machines struggle with the newer titles so it's important to be realistic with expectations. Most 2d vector games work really well. Some 3d games work too.
Making modifications in the mame.ini file can help improve performance, check out what the options do here http://manpages.ubuntu.com/manpages/precise/man1/mame.1.html
Sometimes, the configurations that work well for one game, hinder another. I've tried making a universal configuration that works well in all cases but it really needs changing for each game. Currently I have a .ini file that's in the process of being set up with options that I can set up that are universal to all games and then setting specific ones in specific files targeted to that game.
Mame can be used at the command line to run a game without the mame launcher
mame [name of game file]
The location of the game doesn't need to be given as a parameter, just the name of the file (not the name of the game).
Installing Gnome-Video-Arcade gives a different cleaner user interface plus it configures games that the normal mame gui doesn't so if you have a particular game that doesn't seem to work, gnome-video-arcade might be able to configure it properly.
Not all game roms work either so it can be trial and error on what's available. Also you might need to download bios's before games will work, these need storing in the roms folder too.,
Now the main system is finished, the next updates are going to follow making a customized enclosure or case for the video console.
For now I'm sharpening my afterburner skills!!