While Optimus Prime is a major character in the game's narrative, he is not playable. You can control various other Autobots like Bumblebee, Ironhide, Jazz, and Ratchet, and even the Decepticons like Megatron, Starscream, and Soundwave.
However, you can enjoy Optimus Prime's presence through cutscenes and dialogue interactions within the game's story.
If you are looking for a game where you can play as Optimus Prime, you might consider other Transformers titles like:
* Transformers: War for Cybertron (2010): This game allows you to play as both Autobots and Decepticons, including Optimus Prime, in a campaign set on Cybertron.
* Transformers: Fall of Cybertron (2012): A sequel to War for Cybertron, this game features a similar gameplay style and allows players to control various characters, including Optimus Prime.
* Transformers: Devastation (2015): This game is a stylized action game with a focus on combat and features playable characters like Optimus Prime, Bumblebee, and others.
I hope this clarifies your question!