This is a 1986 video game developed by ISCO and published by Takara in Japan for the Famicom. It is based on the popular toyline Transformers. The game was made available on the Wii's Virtual Console service on June 10, 2008.

The game stars Autobot protagonist Ultra Magnus. The titular Mystery is the identity of Optimus Prime's (referred to in the title as "Convoy") killer, as the 1986 film did not see a Japanese release for another four years. Thus, Optimus Prime's death was not adequately explained to the Japanese audience; this game was intended to capitalize on that gap.

The player controls Ultra Magnus, who must shoot his way through 10 horizontally and vertically scrolling levels consisting of various Decepticon enemies, with a boss fight at the end of each level. He can transform into a car carrier, which makes it easier for him to avoid enemy attacks, drive through narrow entrances and shoot enemies that are flying above him. Along the way, he can also pick up various power-ups which can give him wider ranging firepower or even the ability to fly. There are two Warp Zones within the game; they can be found by rescuing Bumblebee from the Decepticons.

The bosses for each level consist of mostly large Decepticon symbols in different color palettes. The only Deceptions Ultra Magnus actually fights are Megatron, who for unexplained reasons is the penultimate boss, and Trypticon (known in Japan as Dinosaurer), the final boss.

Another playable character in the game is Rodimus Prime, who can be unlocked by collecting the letters that spell Rodimus. One is hidden, sequentially, in levels 1, 2, 4, 5, 7, 8, and 9. However, though his vehicle mode has its own graphics, his robot-mode sprite is Ultra Magnus in Rodimus's palette