As the head of the Amadeus Syndicate, he helps Morden to obtain new weaponry, and also creating his own army. He is the final boss of Metal Slug 4. He has 3 types of robots. Two robots, as well as a central computer used to control various weaponry in the vicinity. First computer is armed with missile launchers, a pincer claw, electric cannons, and ring laser. The second computer is armed with a pincer claw, built-in mini-guns, satellites cannon, and giant saw. The central main computer controls multiple laser guns, laser cannon, drone and a wave that attempts to kill you by covering the whole area. After defeating him, the base begins to collapse while he is still stuck inside the last machine. It is unknown if he survived the destruction of the base.
The ASY (Amadeus Syndicate Army) was an army created and used by the Amadeus Syndicate. This army was composed by volunteers and Morden's army veterans. The army adopted the uniform and the Stahlhelm, only changed to blue. They adopted both Regular and Rebel Army equipment for use in their army.
Amadeus appears several times in Metal Slug Attack, both in Extra Ops and Another Story.
In "Amadeus' Revenge" Extra Ops, he tests out a new Type γ Mother Computer and is delighted with the results. When confronted by the clumsy Rumi, he attempts to kill her with lasers, but she dodges them. She then throws grenades which seemingly miss, causing him to laugh. The grenades suddenly reappear again and explode, destroying the Mother Computer, though he survives, and is clearly not pleased.
He appears in Another Story in the chapter "Guilty Child", where Amadeus soldiers bring Abigail to him. When Abigail warns him to speak carefully, he is confused with what is happening. Amadeus recognizes Allen and remarks about how he's grown, resulting in Allen wondering if Amadeus is getting senile. Allen then tells him that his robots attacked them on the way to the headquarters, and he takes out a holographic keyboard, showing them he controls the robots. He stops when Abigail asks him why he created robotic versions of Morden with a little girl's voice. Amadeus tries to stop White Baby from causing more havoc, but is helpless as he is forced into a Mother Computer to battle the two.
After the battle, he tries to stop White Baby from leaving but is unable to. He apologizes to the rebel officers for causing unnecessary trouble and explains White Baby to them. He offers to help them by finding White Baby before it can cause more trouble. When Abigail tells him that they will destroy her, he silently agrees, something which Allen interprets as a parent worrying for their child.
Although Amadeus' personality is never shown during the main game, In Metal Slug 4, he unleashes a sinister, maniacal laugh upon seeing the player.
|The battle begins as Amadeus mounts the Type α Mother Computer. Its attacks consist of opening its hatch to launch missiles, using a pincer claw to attack the players, shooting its electric cannon, and firing a ring-shaped laser.|
|After destroying the Type α, Amadeus will switch to the Type β Mother Computer. It attacks by opening its front and firing multiple rounds from its mini-guns, sending out a buzz saw, and launching satellite drones which attack by firing energy projectiles.|
|Once the player successfully destroys the two Mother Computers, he will finally take control of the central machine. This computer's attacks consist of firing horizontal lasers from the left and right, releasing many lasers that ricochet around the screen, and calling two robots that appear from the left and right to fire further blasts, shooting laser beams first towards the floor, then at a forty-five degree angle towards the players.|
|In Metal Slug Attack a third version of the Mother Computer appears as an unlockable unit.|
Like all of Metal Slug 4 bosses, which were made using sprites from previous Metal Slug games, Amadeus himself uses a recycled sprite from Parker. He was designed to look like a mad scientist.
Of note, Amadeus possesses a number of similarities to other well-known characters:
- There is a similarity, albeit vague, to Dr. Albert Wily from Capcom's Mega Man game series.
- Another slight similarity to Dr. Wily lies in the fact that Amadeus has a UFO like command module that he can attach to his larger assault components, in a similar way to the Wily Capsule.
- Amadeus appearance also somewhat resembles that of Doc Brown from the Back to the Future film series.
- His command center design bears more than a passing resemblance to the B-9 Robot from the classic sci-fi series "Lost in Space". Strangely enough, the B-9 is also known to associate with another scientist of dubious character, Doctor Zachary Smith.
- He also plays a similar role of Dr. Eggman / Dr. Ivo Robotnik, the main villain in Sega's Sonic the Hedgehog series, being that he has a control pod that can fit into any machine he has created, using them during the battle.
- One other similarity can be found in James McCullen / Destro from the G.I. Joe mythos. Both Destro and Amadeus are the primary weapons supplier to terrorist organizations, with Destro being the power behind M.A.R.S. (Military Armaments Research Syndicate), one of the largest manufacturer of state-of-the-art weaponries. Like Amadeus, Destro also employs his own personal army, the Iron Grenadiers.
- Amadeus, as previously mentioned, reuses the sprite for Parker, the businessman/representative of the fictional video game company "Duke", who had his briefcase stolen by the player in Metal Slug 2/X.
- Amadeus' robots are the only bosses in Metal Slug 4 that aren't made of recycled sprites from previous games.
- The laser turrets in the third phase of the boss fight is a recycled sprite of the Supervisory Camera.
- Amadeus and Invader Queen are only final bosses which have their own final boss theme.
- After Metal Slug 4, he has since reappeared in Metal Slug Defense (ver. 1.38.0) during the "Amadeus Attack" event. His robot can be purchased in the game's store via coins collected in the Event Area.
- On Metal Slug Attack, he is featured as a Daily Boss on Friday-Saturday. Only his "α" and "β" computers appear in the game.
- Later, in the Extra Ops "CODE: ASSAULT", he reappears as the main boss, again with the previously mentioned computers only. If the player clears all the levels on "Easy" difficulty, Amadeus can be ontained as a deployable unit.
- Unlike Metal Slug Defense, both computers ("α" and "β") are considered one unit (just as Emain Macha on said game). Once "α" is destroyed, "β" will appear from the base, but only if the player has unlocked a determined skill. This could explain the unit's expensive AP cost (which is increased to 2000 in Silver, 1800 in Gold and 1600 in Diamond/Platinum).
- He shares his name, "Amadeus", with famous Classical era composer Wolfgang Amadeus Mozart.
- If you are too close to the Type: α, the energy projectiles will not hit you, instead it will stay in mid-air until it fades, this is an advantage to be used against Type: α.