Metal Slug 2 (and, therefore, Metal Slug X) set the bar so high for shoot' em up games that it was only surpassed by its own sequels. You are looking at a title where you (normally) need to advance from left to right while you smash a whole that is after you.
In spite of its simple premise, Metal Slug X will keep on surprising you. To begin with, get ready for literally rampant action: one minute you'll be aboard a jet plane destroying a moving train and the next you'll be climbing a tower while escaping from a monster-shaped robot.
But the action is not the only thing that will vary in the game: eat too much fruit and you'll turn into an obese but mortal hero; once in a while you'll run into vehicles that radically change playability; and don't forget the enormous final bosses, which are also true visual spectacles. You'll die many times because you'll be paying more attention to the details happening on the screen than to what's happening to your character! (source)
