Metal Slug 4 is a video game that is part of the very famous series of videogames "Metal Slug", saga created by SNK was originally born on Neo Geo.
After having depopulated for the Neo Geo, Metal Slug has been converted for many other platforms, including the PlayStation 2, the Neo Geo Pocket Color, the Game Boy Advance, the Sega Saturn, the Nintendo DS, the Xbox and the Xbox 360. Metal Slug it is also available for PC, Android and iOS.
Also for PlayStation 2, but also for Wii and PlayStation Portable, an anthology (called Anthology) has been published which contains the first seven chapters of the saga, Metal Slug X included. Here are some code useful to finish the game and to unlock extra content.
Beat the game with each character to unlock a new picture each time you beat the game.
After defeating the final boss you will find yourself in a room where you will have to escape from a series of explosions. Instead of running away from these explosions, let your character be killed… you will see an alternate ending.
TURNING INTO A MONKEY
In the last level, if you kill the scientists with guns, they will drop red potions from time to time. If you collect them you will immediately transform into a monkey. Once you are a monkey, you can cling to the rafters and handle the gun with your feet. To become human, you must either find a blue potion or die.