There are six different Autobots that can be played, including Optimus Prime, Hound, Drift, Grimlock, Bumblebee and Crosshairs. Each character has different ratings in Hit Points, Melee and Ranged. You will start out with only Bumblebee and can unlock most of the other characters by earning stars for completing missions. Each new character costs ten stars. You can increase an Autobot's stats with new gear. Gear can be purchased with Cargo Packs, which in turn can be purchased with Energon Packs. The most common Energon is Blue. Green Energon Packs are uncommon, and Rare Energon Packs are rare. The rarer the packs used to buy Cargo, the better the gear. Gear can also be upgraded and leveled up with Energon Shards that are given as mission rewards.