|Founded||2030-2031 (exact date unknown)|
|Headquarters||Unnamed communications facility, location unknown (somewhere in Oceania)|
|Area of Operations||Worldwide|
|Enemies With||Regular Army|
Ptolemaic Army (Metal Slug Attack)
Martians (Metal Slug Attack)
Invaders (Metal Slug Attack)
|Affiliated With||Rebel Army|
The Amadeus Syndicate are the main antagonists of Metal Slug 4.
The Amadeus Syndicate is a highly technological advanced paramilitary organization and rogue scientific corporation affiliated with the Rebel Army. Their goals are idealistic in nature and center about better understanding the forces that govern the universe, no matter the cost. To do so free from legal constraints they rely on Morden's resources and alliance to test out their prototypes and conduct experiments.
The Amadeus Syndicate is made up of unethical scientists, Rebels and mercenaries. Due to Metal Slug 4 reusing weapons and infantry from other armies, it appears as a small rogue organization. The Syndicate is in the Independent Faction in Metal Slug Defense and Metal Slug Attack because of this, although the latter game expands their forces with new members and tech.
With the money the Amadeus Syndicate were able to obtain from their banks around the world, they became a very rich company. Their leader, the tentatively named Doctor, was a friend of Morden, and when the Rebel Army lost their funding and was utterly defeated a third time (after the events of Metal Slug 6) the Syndicate helped them by supplying the Rebel Army with more mercenary troops, advanced weapons, and vehicles.
In Metal Slug Attack, the Syndicate's forces have been expanded and now sport a violet and gray motif. Since Regular Army soldiers make an appearance in the game (who also sport blue uniforms, which were used in Metal Slug 4 by the Syndicate, albeit a darker hue), most Syndicate members now wear a violet uniform. The Syndicate also developed numerous robots and machines based off the Rebel Army's designs with a few modifications to them. They are still on good terms with the Rebel Army and provide them with new equipment from time to time.
Amadeus troops consist of infantry, advanced combat robots, and AI. Soldiers who work directly with the Syndicate only have two main uniform colors: purple and navy blue.
|Blue Syndicate Uniform: Uniform worn by Amadeus soldiers in Metal Slug 4 and Metal Slug Infinity.|
|Purple Syndicate Uniform: Alternate color uniform worn by Amadeus soldiers. Used exclusively on Metal Slug Attack.|
|Hazmat Suit: Protection suit worn by soldiers in hazardous environments or when handling viruses, biological hazards, or supernatural based weapons.|
|Lab Coat: Distinctive coat worn by the Syndicate scientists.|
Amadeus Scientist Board
Other Known Members
Units derived from the Rebels are stronger, often remote controlled or AI guided, and painted in grey and purple.
|Di-Cokka (Amadeus): Enhanced variant of the Rebel Di-Cokka.|
|Nop-03 Sarubia (Amadeus): Enhanced variant of the Rebel Sarubia.|
|M-15A Bradley (Amadeus): Armored and enhanced variant of the M-15A.|
|Proyutom (Amadeus): The Professor's main transport hijacked by the Valerian AI.|
|Space Tank (Amadeus): Mass produced enhanced variant of Morden's Space Tank. Guided by the Valerian AI.|
Bosses and Prototypes
These are the unique vehicles in possession of the Amadeus Syndicate designed to support the Rebels' large scale operations and vigilance.
|Amadeus Mother Computer: The organization's mainframe and ultimate weapon.|
|Brave Guerrier: Armored support blimp for long range air support.|
|Toschka Dalanue: Armored watchtower designed for the Rebel Army in Metal Slug 4.|
|The Iron: Improved Iron Nokana chassis with heavy weapons.|
|Big John: Manned animatronic defense system equipped with cruise missiles and biological weapons.|
|Sea Satan: Submarine based on the Rebels' Hozmi. Also has airship variants.|
|Iron Fortress: An improved and enhanced Iron built to accommodate a custom AI. Completely autonomous and modular.|
|Dai-Manji (Amadeus): Martian spacecraft hijacked by the Valerian AI.|
|Hairbuster Riberts (Amadeus): Enhanced variant of the Rebels' bomber.|
|Hi-Do (Amadeus): Enhanced variant of the Rebels' multirole helicopter.|
|Regular Army||P.F. Squad | S.P.A.R.R.O.W.S | Ikari Warriors | Metal Device Project|
|Rebel Army||Rebel Infantry | Arabian Infantry | Future Rebels | ACE | Blaze Brigade | "Frozen Brigade"|
|Large Scale||Martians | Amadeus Syndicate | Ptolemaic Army | Invaders | Oguma Corporation|
|Small Scale||Japonese Army (Division 6) | Pirates | KOF Team | Mummy Army | Red Goblin Society | Secret Sect | Vampires | "World Military Corp." | Yuki Tsuki Hana|