MAME4droid emulates arcade games supported by original MAME 0.37 b 5 plus some additional games from newer MAME versions. This version emulates over 2000 different romsets. Please, try to understand that that with that amount of games, some will run better than others and some might not. MAME ROMs: Here are all 1,001 ROMs that I have that work with MacMame! Back to the MacMame.
Like many other poor souls not privy to MAME ROMs and emulators I struggled to get my ROMs to work. It seemed like every time someone tried to explain it on a forum or blog post I left feeling more confused or discouraged, so I put it off. It's one of the most confusing parts of RetroPie. Finally I came across that had a no bullshit answer and actual instructions of what to do and where to place the files.
EDIT: Here it is summarized below. For more details use the link to the post. Find a 0.78 MAME romset. Copy the roms you want over to the mame-libretro folder.
Copy the bios files in the romset over to the /home/pi/RetroPie/BIOS/mame2003 folder. Just copy them all if you're not sure what does what, doesn't take up a ton of space. Include the samples subfolder. Reboot Emulation Station and the roms will appear.
I was finally able to get Metal Slug working! Why didn't the main have a simple example like this? It could have helped so many others that came before me. So, I updated the Wiki with some information that I think will really help others and would have helped me when I was struggling. I modified the table to remove the useless 'BIOS extension' column where each entry was '.zip' and added a paragraph with an example showing exactly what you need to do to get a MAME ROM working (along with a few other improvements). TL;DR After struggling for weeks to get MAME ROMs to load correctly I finally stumbled upon a and finally got my ROMs to work, which inspired me to update the official.
EDIT: Some simple, and great advice from comments below. 2 approaches: (1) To save yourself the headache of wondering whether you have the right files, try downloading the full romsets and throw those in the arcade directory. (2) Copy samples and BIOS into proper directories, then if filesnames have similar names such as game1a.zip, game1b.zip, etc. And make sure you keep these together. EDIT 2: About the mysterious 'samples' directory, thx: There's a folder called samples in the romset that contains sound files for games. Just copy the entire thing over to /home/pi/RetroPie/BIOS/mame2003/samples/ EDIT 3: It just dawned on me that a FAQ and TIPS sections on the GitHub Wiki MAME section would probably be really helpful. I will try to compile common questions and answers tonight as a start.
More important: those with knowledge of these things should contribute to the Wiki so the RetroPie community needs it and can certainly benefit from it. EDIT 4: Removed a link. I appreciate the effort but i don't actually think your update is that good. What if it's a clone rom that needs a parent? How do you know what BIOS it needs? I would always suggest acquiring full romsets and putting the whole lot across. Why didn't the main GitHub Wiki have a simple example like this?
It could have helped so many others that came before me. Because people never want the right answer (full romset, of the exact right version, in the right place), they always want to download random roms, or ask why they have to keep 15GB of stuff to play pacman, etc.
We already have one of those people in this thread. You end up having to cover so many questions that it's impossible to keep simple. The best thing that could be done for the guide IMO is moving ALL the clrmamepro stuff to a separate page or removed entirely (you shouldn't actually need to do any of that stuff - all the full romsets we use are readily available).
The slightly more complex but still simple answer: move samples and bioses over to the right place, then you can copy and paste roms as you desire without worrying about dependencies. But that's wrong. If you have a split set (which most of them are), then pacman.zip will not work without puckman.zip, etc. The clone/parent relationship is a huge pitfall if you don't have the full set in your directory. Someone transfers the 'USA' (clone) version of street fighter 2 and it won't work, because the 'WORLD' (parent) version isn't present, etc. I'm a big, big fan of simple explanations, and cutting the wiki page right down, but the simple explanation has to be to get the whole set. If people don't like that, they have to be prepared to learn about how MAME works, and that's not simple.