X-Mame the UNIX/X11 port of Mame project. It makes Mame arcade emulator available on *ix machines using the X11R6 X-Window system (and Linux ones using SVGAlib too).
Mame is a virtual machine emulator: it includes a Z80, 6502 and lastly I86 uP emulators, joined to several arcade machine hardware emulators. Each arcade emulator contains a full description about hardware, mem maps, video, sounds and so, making possible that if you have original ROM images of a supported arcade game, you can play the game.
You NEED the rom images to play a game: this is not a game emulator, just an arcade machine one.