If the player happens to be fat while using these heavier weapons, they appear differently and can cause even more damage. Each deals more damage than their normal counterpart, has a different appearance and a wider (or longer) area of impact.

Stronger versions like the heavy machine gun, flameshot, shotgun, laser rifle, and rocket launcher are available.

Many environmental elements have different reactions when shot, such as exploding with unexpected results or randomly spewing out items or enemies.

There are more power-ups, POWs, and items (particularly food) in each mission.

Vehicle types and locations are different.

All levels contain an increased enemy count and new enemy placements, as well as different enemy characters, and new boss placements.

It is now possible for the player character to become fat by collecting food items in every stage after Mission 2 in the original game, the obese transformation was only possible in Mission 4.

Instead of individual levels being set at either day or night, the stages can take place at dusk, twilight, or sunset.

Many stages have the time of day changed.

Much of the music has been remixed or altered.

Metal Slug X also introduced some new elements to the game system

It fixed slowdown problems from the original game, and increased the difficulty. An upgraded version of Metal Slug 2, titled Metal Slug X, was released in March 1999 for the Neo Geo MVS.

Metal slug 1 ps1