In 2005, G.I. Joe returned to television with G.I. Joe: Sigma 6, the code name for a new group of G.I. Joe heroes with highly specialized capabilities, which they use to protect the world from the Cobra Commander and his evil forces. Sigma 6 featured many of the most popular and well-known G.I. Joe characters, such as Duke, Snake Eyes, Heavy Duty, Scarlett and Tunnel Rat, as well as a new hero, Long Range. It ran for twenty-six episodes.
The premise is that it is now the 21st century, and G.I. Joe is still fighting to prevent Cobra taking over the world. An ambush in the Arctic and the subsequent escape of Cobra Commander from prison, lead the Joes to believe something bigger is going on. After a major attack by Cobra on the G.I. Joe Team’s headquarters, the Joes are forced to retaliate. This time, they are equipped with Sigma suits. Designed by Hi-Tech, these special body suits protect the Joes from Cobra’s laser blasts and, in addition, enhance their abilities. The Joes are now code named Sigma 6.
Following on from its previous cartoon incarnations Sigma 6 has Duke as the G.I. Joe commander. Scarlett is upgraded to second in command after Duke. Tunnel Rat’s appearance and personality varied greatly from his appearance in A Real American Hero series. Here, he is a bug-eating, unorthodox infiltration and demolitions expert. Heavy Duty seems to have retained his personality from Spy Troops and Valor vs. Venom, serving as the team’s weapons expert. Added to the team is a tracker, Spirit Iron-Knife, and his falcon Billy, who retains his strong and shamanist personality, as well as the team sniper and transportation specialist Long Range. Hi-Tech serves as the team’s technician, mechanic, etc. Jinx, Kamakura and Snake Eyes function as the team’s ninja unit. Snake Eyes has remained the silent deadly ninja commando with Jinx and Kamakura as his students. Hawk was last seen in a healthy state at the end of Valor vs. Venom but his appearance in Sigma 6 indicates otherwise. He is seen in a hospital where Duke visited him.
At the start of Season 2, Lt. Stone (an apparent old friend of Duke’s) arrives and joins the team under orders of Hawk and provides them with a new seafaring base, the Sea Titan, as well as his personal attack copter, the Dragonhawk, which will also be used as a drop ship for the team’s vehicles that can be carried by the Dragonhawk, like the Ninja Hovercycle, the Night Ranger Quad and the V.A.M.P.. Along with Stone is the soldier Firefly (who betrays the team and captures all but Duke and Hi-Tech in season 2 episode 7 “Revelations”).
The changes are not limited to the Joe Team. Cobra Commander had his appearance greatly overhauled and, likewise, his personality. No longer comical, he is now a more deadly adversary, closer to his standard portrayal in the comics, however he has retained his cartoon counterpart’s love of grandiose schemes. Destro is now more clearly aligned with Cobra and together with the Commander and the Baroness, they truly form the Cobra Triumvirate. Meanwhile, Overkill is upgraded from a lowly lab assistant to a scheming cybernetic chief scientist who is stuck inside a giant glass tube. Zartan remains Cobra’s master of disguise, however his shape shifting and stealth abilities are due to his suit rather than skill and genetic enhancements as in A Real American Hero. The Dreadnoks are now Torch, Buzzer and a new character called Machete (who is loosely based on Ripper). Storm Shadow serves as Cobra’s ninja, however seems more inclined to work with Cobra B.A.T.s, leading the Ninja B.A.T.s into battle. This differs from his original portrayal in A Real American Hero as he has always had more faith in a well trained human as opposed to machines. Though the series is supposed to continue from Valor vs. Venom, in episode 2 “Escape”, Cobra Commander says to Overkill that all his troops should be welcoming him, implying that Overkill was the only absent Cobra member. That claim ignores the presence of characters such as Doctor Mindbender or Slice in Valor vs. Venom.
Sigma 6 also has a recurring man vs. machine theme. Cobra’s forces are often seen to be primarily composed of the Battle Android Troopers or B.A.T.s, while the members of the Cobra Triumvirate all possess some form of cybernetic enhancement or enhanced armored suits, with normal troopers wearing full armored uniforms.