MAME is an amazing program that emulate pretty much every arcade system that ever existed. The only issue is that it can be a bit complicated to setup and a lot of the helpers softwares gravitating around it are imperfect or incomplete. Many friends always ask me to set it up for them and I got tired to maintain these installations. Git version control seemed to be a good way for me to distribute the setup and have my friend update it easily.
This folder is meant to be merged on top of an official download of the MAME 0.229 emulator. On Windows you'll simply have to download and unzip the program. On MacOS we rely on SLDMAME that you can be downloaded here. As the name indicates, this flavor of MAME relies on the SDL framework which will also have to be installed before you can run the emulator. Installation is pretty straight forward but this video tutorial may help.
If you want to use the GUI simply double-click the executable. Press Alt + Enter to go fullscreen. If you want to use the commands, keep reading. Using a terminal, cd to the mame folder and run ./mame [rom_name] for example ./mame sfa3. Since version 0.226, MAME emulates consoles, therefore you can also run ./mame [machine_bios] [rom_name] for example ./mame megadriv sor2. You will notice that MAME will conveniently propose rom name corrections if you type something slightly wrong. I use that all the time. There is a lot of other possibilities when running the emulator through command line and you can have a better idea of what is available by running mame -h.
You can play with the keyboard but the emulator is also already configured to work with four 8BitDo Arcade Sticks. Main keyboard keys for the first player are 1 for start, 5 to insert coin, W A S D for movement and G H J B N M for buttons. The other players are only mapped to joysticks.
An emulator is not worth much without it's roms, unfortunately I cannot provide them as part of that setup for obvious reasons. Therefore you will have to use you imagination to get a hold on these little gems. Once you do, create a roms folder at the root of the mame folder and stick all the .zip files in there. Console BIOS roms should also go in the roms folder, on the other hand, console game roms should go in a separate folder called soft and should be grouped by systems such as megadriv.
A few game developer have been kind enough to declare there game non-commercial and therefore these roms can be downloaded in a totally official manner.