Metal Slug X is a revised version of Metal Slug 2, released in March, 1999 for the Neo Geo MVS. Metal Slug X was developed by SNK Playmore and Nazca Corporation, and published by SNK Playmore. Not only did it fix slowdown problems present in Metal Slug 2, but it increased the difficulty. New weapons and items were also added, such as the Iron Lizard and the Drop Shot. In addition to these changes, enemy placement and bosses were also changed. Metal Slug X was later ported to the Neo Geo AES (in 1999) and the PlayStation (in 2001).
- Enemy Chaser shoots rockets that track down enemies
- Iron Lizard shoots a bomb that travels on ground and explodes when it hits an enemy
- Drop Shot shoots iron balls that bounce on the ground until it hits an enemy
- Super Grenade fires a rocket that travels forward and causes a large explosion.
Game Informer gave the review scores of 6 and 6 out of ten. Jay Fitzlof wrote, "Metal Slug X has plenty of action, with enemies jumping at you from all sides, plenty of weapons and vehicles to try out, and lots of hidden items to discover. The only problem is, assumming you use the unlimited continues, you''ll finish the game in about half and hour... it feels like Metal Slug X would work better on a handheld. In fact I know it would since I thoroughly enjoyed the two Metal Slugs on the Neo Geo Pocket Color only a year ago".