@slobu So, answering your question:

I believe what you may be looking for are "public domain roms". However, I am not sure about whether that means there are restrictions to their distribution. But yes, I am under the impression there are some Roms that are legal to download - not to mention homebrew games for each system. That might be a worthy check as well. As for your own games, I think that's always a positive thing, ultimately depending on how accessible it is to install/set them up, and assuming that you have the actual rights to their distribution. It's definitely a generous thing to do, for sure. Are they for any of the emulated systems?

Have a great weekend.

2 years ago I've created a github-project to cleanup all your roms.
maybe this is something for you.

https://github.com/TobiasKoller/RomSetManager

Best Regards
Tobias

@massaki
I've never used the Mayflash adapters but I do read about others having issues with them on this forum. You might search the forums and see what everyone is doing to get it working.

I've also never used the Buffalo SNES USB controller but I think they work pretty well. Might not have enough buttons for PSX, PSP, Dreamcast and N64 games but those are the systems that are at the very limits of the RPi 3, meaning some games work, some have slow downs and most don't work at all. Out of those 4, you'll probably have the most luck with PSX games.

I use Xbox 360 controllers (wired & wireless) and they work very well. I've heard the PS3 controllers work well also.

@herb_fargus Thank you! This is absolutely amazing! Thanks for your hard work putting it together!