Transformers: Mystery of Convoy

Transformers: Convoy no Nazo (English: Mystery of Optimus Prime) was a video game for the Famicom (the Japanese version of the Nintendo Entertainment System). The player controlled Ultra Magnus on his mission to find the whereabouts of the missing Optimus Prime. Along his quest, Ultra Magnus faces various Decepticon threats, including Starscream-like fighter jets, the Combiners Bruticus and Menasor, and a final battle against Trypticon.

Upon completing the game, the player was given the option of starting again at level one, this time playing as Rodimus Prime. Rodimus Prime had a new sprite for his vehicle mode, but his robot mode was simply a recolored Ultra Magnus.

Despite his name being in the title of the game, the only time Optimus Prime appears in-game is during the start screen, when his head explodes and reassembles as the player's sprite.

From Teletraan I: The Transformers Wiki, a Wikia wiki.