MX vs. ATV Untamed on PSP has players competing in an eight-series X-Cross tournament. Events take place in indoor stadiums and outdoor courses, each offering plenty of spots to perform more than 50 tricks. Terrain includes a mix of sand, snow, dirt, and asphalt, with hazards such water, logs, and rocks adding a degree of challenge. While the obvious focus is on racing MX bikes and ATVs, players can also slip behind the wheel of a monster truck, dune buggy, ORV, 4x4 golf cart, trophy truck, and a sand rail.
Exclusive to the PSP version are in-game achievements or milestones. The latter offers more than 50 scenarios to complete to earn a bronze, silver, or gold medal. Examples of milestones, which can be accomplished in any of the main game modes, are performing tricks over water, staying in the air for a set duration, landing a specific stunt, and more. Eight professional racers are available to play as or against, including Ricky Carmichael, Davi Millsaps, Kory Ellis, and Dana Creech.