Retroarch is known as one of the best Cross-platform frontends for emulators game engines, video games, media players, and some other applications. This is open-source software.
Retroarch runs those programs that are converted by dynamic libraries called libretro cores, using several user interfaces. These Programs may be a command-line interface, a few graphical user interfaces (GUI) optimized for gamepads several input-output drivers, etc.
Retroarch BIOS Pack
This Retroarch BIOS Pack contains some awesome game ROMs. You can download the pack from the bellow.
Also See: ROMs pack