An emulator is nothing else than a program that simulates being a machine, this trick is very useful in the world of computing (and video games) to make sure that the machines that are now old and useless aren't forgotten. An emulator can launch any of the games designed for the machine that it emulates on a computer. Thanks to Neo MAME32, we'll be able to play the classics for SNK, Neo Geo or Atari.
The MAME project managed that many game arcade games weren't forgotten and that their ROMs were distributed over the Internet, but some small errors made it necessary to launch Neo MAME32, an emulator that managed to improve the original and make it easier for the users to enjoy old arcade games.
Nowadays, MAME and Neo MAME32 support almost all arcade machines and the vast majority of games that appeared for them, including classics like Bust-a-Move, Metal Slug or Bomberman.