: There was a massive batch of unlicensed NES/Famicom multi-game cartridges made playable, along with significant software list updates for Apple II, FM Towns, and PC-98. Rom Set Considerations
MAME itself is legal, but downloading ROM sets is legally gray. ROMs are copyrighted, so you should only use ROMs from games you physically own. For preservation, projects like the Internet Archive have hosted older sets, but always check your local laws. mame 0.235 rom set