Getter Robo Armageddon ( 真(チェンジ!!)ゲッターロボ~世界最後の日 Shin (Chenji!!) Getta Robo~Sekai Saigo no Hi?, True (Change!!) Getter Robo: The Last Day of the World), often simply referred to as Change!! Getter Robo in Japan, is an original video animation released in 1998 by Bandai Visual' s Emotion label as part of its 15th anniversary. The OVA is based on the manga and anime series Getter Robo, created by Ken Ishikawa with input from Go Nagai. The series, however, owes more to the manga than the 1970s animated adaptation, with designs closer to those of Ishikawa's original art, and a darker, more serious theme than the anime. It has a direct prequel in the form of the audio drama 'Getter Robo: The Moon Wars', and is not a sequel to the 1970s TV series (a common misconception).
The plot opens some time after the Moon Wars, where things for the original cast have taken a turn for the worse. The main character and pilot of Getter-1, Ryoma Nagare, has been framed for the murder of the Getter Machine builder Dr. Saotome after the death of Saotome's daughter, Michiru. However, he is released from jail and is reunited on Earth—unhappily—with his old allies, Hayato Jin (who set up and then testified against Ryouma) and Musashi Tomoe (who displays distrust towards Ryoma for presumably traumatizing Genki after Michiru's death and Dr. Saotome's murder). They were summoned to fight none other than Dr. Saotome himself who has seemingly risen from the grave to threaten humanity with his ultimate creation—and most dangerous weapon—Shin Getter Dragon, a massive weapon powered by the same cosmic Getter Rays which gave life to their old weapons. However, their efforts to stop Dr. Saotome, not to mention an overzealous Japanese Defense Force who go to extremes, are in vain as the government launched nuclear weapons on Shin Dragon.
The resulting explosion and shock wave of Getter Rays wipes out 99% of the human population worldwide. Thirteen years after this catastrophe, as humanity clings desperately to life, the re-emerged Invaders threaten Earth once more. The only safeguard against this alien threat is a giant robot that emerges from the wreckage of the nuclear blast—Shin Getter Robo—piloted by an artificially created human named Go. With the help of Hayato's Super Robot Army and Go's co-pilots Kei and Gai, Shin Getter fights to keep humanity's dreams alive.
Later, Ryoma returns piloting the Black Getter to aid the new Getter team against Dr. Saotome who returns with Stinger and Cowen when Shin Getter Dragon re-activates and continues its evolution. It was also revealed that Kei was Dr. Saotome's younger daughter and Michiru's younger sister, Genki, who was adopted by Benkei. Soon the Invaders put their true plan into action by transforming Jupiter into a Getter Ray Sun and sending Ganymede, one of its moons, on a collision course with Earth; prompting both the old and new Getter teams to spring into action to save the planet.
As a whole, the response to this OVA was positive, thanks in large part to its distinctly retro character designs combined with high-quality animation; however, there are those fans who felt that the plot was convoluted (not helped by a directorial shift after the third episode) and strayed too far from the original TV series' characters. However, the effects of the OVA were long-lasting, as it led to the creation of two other Getter OVAs (Shin Getter Robo vs. Neo Getter Robo and New Getter Robo), as well as the revival of the Mazinger Z franchise with Mazinkaiser in 2001. Unlike other series produced by Dynamic Planning, as Getter Robo Armageddon's setting departs with the standard setting of the Getter world (especially towards the manga version). So far, Armageddon's appearance in Super Robot Wars Series is very little as other Getter Robo and Mazinger series counterparts do (Only Destiny involved its storyline, until the 2011 announcement of Super Robot Wars Z 2, Super Robot Wars Z 3; and a Black Getter, modified to room 3 pilots, being placed as a hidden mech in Alpha Series). However, it participated in robot action game Another Century's Episode 3: The Final instead, which differs from other Dynamic Planning's production that mostly involved in strategy, or shooting games.