It was the first game in the series to allow players to carry two power-ups at once and switch between them.

However, the emulation community eventually achieved near-perfect emulation of the Atomiswave hardware. Today, the definitive way to experience the ROM is via MAME, which preserves the smooth framerate, original music, and crisp visuals of the arcade release.

: For the first time, characters aren't just cosmetic swaps. The original four (Marco, Tarma, Eri, Fio) are joined by Ralf Jones and Clark Still from Ikari Warriors and The King of Fighters . Marco : Deals double damage with his default pistol.

: Starts every life with a Heavy Machine Gun and has a 50% resupply bonus.

Unlike its predecessors ( Metal Slug 1 through 5 ), which were designed for the 1990s-era Neo Geo MVS hardware, Metal Slug 6 was built for the Atomiswave. This hardware had significantly more RAM and different processing capabilities.

Without the ROM and the emulators that run it, this pivotal chapter of the series would be largely unplayable as original arcade hardware continues to fail and become more expensive.