It was originally released in 1998 for the Neo-Geo MVS arcade platform as the sequel to the 1996 game Metal Slug.

The game added several new features to the gameplay of the original Metal Slug, such as new weapons, vehicles and the ability to transform the character.

Gameplay in Metal Slug 2 is similar to the previous game; the player must shoot constantly at a continual stream of enemies in order to reach the end of each level.

On the way through each level, the player can find numerous weapon upgrades and "Metal Slug" tanks.

The tank is known as the SV-001 ("SV" stands for Super Vehicle), which increases the player's offense and considerably adds to their defense.

The first is Hyakutaro Ichimonji, a prisoner who, when rescued, will fight alongside the player, throwing Hadouken balls at enemies, or roundhouse kicking them if they get within melee range.

Marco Rossi and Lt. Tarma Roving of Peregrine Falcon Strike Force defeated and killed the evil General Morden, who had staged a coup d'état against the worlds' governments.

They have begun to act in unison, and army intelligence concludes that the only way this could happen is if Morden is still alive and is attempting a new coup.

An ad hoc alliance is formed between the Peregrine Falcon Strike Force and General Morden's army to combat the greater alien threat.

The game used a modified version of the engine from Metal Slug 3, which eliminated the slowdown problems of the original.

[6][7][8][9] The original arcade version of Metal Slug X became available on Nintendo Switch via ACA Neo Geo in 2017.

[18] GameSpot's Ryan Davis scored it 8.2 out of 10, writing: "What really separates Metal Slug X from the rest of the crowd is its tongue-in-cheek presentation.

This skewed sense of humor, combined with its frenzied gameplay, gives the game a unique flavor and makes it one of the best side-scrolling shooters out there".

[26] Scott Steinberg reviewed the PlayStation version of Metal Slug X for Next Generation, rating it three stars out of five, and stated that "a derivative but instantly endearing military shooter that earns its stripes".

However, if you're simply looking for the best-playing game of the two, Metal Slug X outshines its closely related cousin with a simple formula of "more, more, and more".