PSi writes: "The last time we saw Metal Slug on PSP was the tremendously entertaining Metal Slug Anthology, which gathered together a decade's worth of gaming action. Metal Slug XX is like the revival games we've seen from a few franchises like Mega Man, which takes the old formula out for a new spin. The modern-day gaming equivalent of a reunion tour for aging rockers, Metal Slug XX is worth every dollar to fans of the franchise. If you haven't played the classic titles that led up to this, Anthology is a good primer, but not "required reading" before you can enjoy Metal Slug XX. Everything about Metal Slug XX is retro, including classic characters that have been part of the action since Day One. A couple of new friends join the party, drafted from King of Fighters, but your favorites are all present and accounted for."