Metal Slug 6

Metal Slug 6 (メタルスラッグ 6) is a run and gun video game for the Sammy Atomiswave arcade platform in the Metal Slug series. It was released in 2006. There was a PS2 port in September 14, 2006. It is also featured in Metal Slug Anthology for the Wii, PlayStation 2 and PlayStation Portable.

Gameplay
Metal Slug 6 returns to the Rebel-Martian alliance featured in Metal Slugs 2, X, and 3, but on a much broader scale. Rather than repeating the previous games' events of the Martians breaking the alliance and the Rebels assisting the player in turn, the player now teams up with the Rebels and Martians to combat an even greater threat.

There are now two modes of play the player can choose from right at the beginning: Easy and Hard. Easy mode lowers the difficulty of the game and changes the player's default weapon to the Heavy Machine Gun; however, the game ends just before the fifth and final mission.

As with previous installments, Metal Slug 6 adds a number of new Slugs as well as a new weapon, the Zantetsu Sword, which allows the player's melee weapon to emit lethal energy waves that can neutralize enemy firepower.

New techniques are now present, activated through certain button combinations. Characters can now throw away one gun power-up's worth of ammunition, to give to the other player or simply discard altogether. A secondary melee attack is also available. Conversely, the sliding technique from Metal Slug 5 has been removed, and players except Fio and Ralf only receive half as much ammo for special guns.

Metal Slug 6 introduces a new play mechanic dubbed the 'Weapon Stock System'. Two gun power-ups can now be carried at the same time. Players can switch between the two weapons, or simply put them both away in favor of the default weapon. When obtaining a new weapon power-up, it will automatically occupy the inactive slot, or, if both are holstered, replace the less recent weapon of the two.

The score is now multiplied by powers of 2. The faster the speed at which enemies are killed, the higher the power, as a meter at the bottom of the screen shows. When it says "Max" enemies and destructible objects will drop coins for an extra high score.

Characters
The number of playable characters has expanded for the first time since Metal Slug 2; the original team of Marco Rossi, Tarma Roving, Eri Kasamoto and Fio Germi is joined by newcomers Ralf Jones and Clark Still of King of Fighters and Ikari Warriors fame.

As a series first, each playable character now possesses his or her own unique attributes. The amount of ammunition received from weapons, defensive ability of vehicles, and running speed vary from person to person, each of whom possess a special ability:
 * Marco: His default weapon (Pistol on Hard, Heavy Machine Gun on Easy) has twice the ordinary strength.
 * Tarma: While riding in or on a Slug, durability and the effects of power-ups are doubled; additionally, the vulcan cannon's power is increased by 50%. He also is capable of using Vulcan Fix when on or in any vehicle.
 * Fio: Begins each mission with the Heavy Machine Gun (on Easy mode, she begins with the Big Heavy Machine Gun from Metal Slug X and 3). Weapon supply is also increased by 50%.
 * Eri: Receives twice as many grenades upon starting or resupplying. When throwing, she can aim in a specific direction.
 * Ralf: Melee attack speed is doubled, at the expense of weapon and grenade supplies being halved. He can also use the special "Galactica Phantom" attack. Additionally, he can take two hits from most attacks before losing a life. Lastly, he is the only character able to damage vehicles and larger enemies with his melee attacks.
 * Clark: Gets an extra chance at start of respawn. He can perform his "Super Argentine Backbreaker" against most non-vehicle enemies; using it on a vulnerable target grants him temporary invincibility during and after the move, while earning generous amounts of points that increase with each additional enemy thrown.

When all 4 missions are completed on Easy mode, the game says "To be continued", meaning that the game must be played on Hard mode to continue with the final mission and see the ending.

New Slugs
The Metal Slug, Type-R Metal Slug, Slug Flyer and a Slug Gunner prototype make an appearance in the game, as well as some new ones.

Roba Slug: A donkey with a mounted vulcan cannon. Like all Animal Slugs, the donkey provides no protection to the rider. Later on in the level, the Donkey Slug acquires a two-wheeled out-house cart mounted with a Metal Slug cannon that replaces the player's grenade with Metal Slug cannon shots.

Mister Slug: Also called Slug Drilled. A multi-purpose subterranean digger as well as a helicopter. It has retractable drills on the left, right, and bottom sides, which are used to drill into the earth, and sports two vulcan cannons, which can also be used to drill through things by firing bullets into the dirt. The players cannot get out of the Slug, neither can they perform the Metal Slug attack with it. If the Slug Digger is destroyed, the player is killed. Its cannon shot is a mine that stays in place until an enemy touches it or it is shot.

Proto Gunner: It is similar to the Slug Gunner from MS5, but it has no melee attack, it does not have tank mode, and the player is exposed to enemy attacks. Its vulcan cannon is more like that of the Metal Slug and it has vulcan fix system.

Rootmars: Previously the final boss in MS3. The cannon is a shockwave coming from Rootmarks's brain which kills all enemies. If the player rides him, in the ending he, instead of Morden, saves the player.

Ports
The PS2 version of Metal Slug 6 came with extra features:
 * Art Gallery - Concept art of Metal Slug 1 to 6.
 * Sound Gallery - Music from Metal Slug 1 to 6.
 * Game Options - Including difficulty, lives, and violence setting (on: red blood and gore for soldiers and for the new aliens; their gore stays on the ground shortly before disappearing). Two cheats can also be unlocked: infinite ammunition and bombs.
 * Combat School - A modified version of Arcade Mode where skills are tested.

Metal Slug Anthology has an emulated version of Metal Slug 6 included on the disc.