Ben 10: Protector of Earth is a side-scrolling platformer/brawler based on the animated TV series Ben 10. Ben is a boy who uses an alien device, which allows him to transform into several powerful beings, to participate in the usual superhero activities. In the game, a drone absorbs most of the device's DNA, leaving Ben only with a few powers. The game is spent with travelling all over the world in the quest to get the full power back.
The levels consists of Ben moving from left to right while fighting against enemies. In the usual brawler fashion, fights are restricted to a small area and all enemies (often additional baddies spawn during the fight) have to be dispatched before moving on. Between combat, there are platforming sections in which Ben has to jump over gaps. However, the main gimmick of the game is Ben's ability to transform into five other beings in total: Cannonbolt (walks slowly, but can transform into a ball and - Sonic-style - roll around the levels), Heatblast (fire-based, can neutralize burning platforms), Fourarms (mostly a strong fighter), Wildvine (can stretch his arm to reach special plants or attack from a range) and XLR8 (has a high double jump and can teleport).
Besides using their abilities for fighting enemies and bosses (which require special strategies), Ben also needs to use their special powers in order to progress in the platforming sections. However, every transformation takes power which can be filled up by collecting energy balls. While this is not much of a problem in the platforming sections (when completely depleted, a part of the gauge automatically fills up after a few seconds), it may create problems when fighting.
In multiplayer, up to eight players compete in destroying as many cars as possible.