Cowabunga! Take control of your favourite turtle ninjas as you play through the events of the 2007 CGI movie. Leonardo returns from his meditation in South America to find his family in disarray, and crime on the rise in New York. A mysterious figure calling himself the "Nightwatcher" has turned up, and a shadowy rich man named Winters seems to be in cahoots with the remnants of the Foot Clan. Only the Ninja Turtles can clean up the streets!

TMNT is an action game, similar to Prince of Persia: The Sands of Time. Play as Leonardo, Michelangelo, Raphael and Donatello, swapping on the fly and using special co-operative moves to help your brothers in battle. Each turtle, being a ninja, can perform moves like double jumping, running along and up walls, gripping onto tiny cracks in the walls, and jumping from wall to wall to scale dizzying heights. Most of the game is spent making your way to the next destination by using your ninja moves to explore New York. Each character also has their own special move: Leo can traverse through walls, Raph can use his Sais to scale particular surfaces, Mikey can use his Nunchucks as helicopters to float for a short period, and Don can pole vault across long gaps with his Bo Staff.

Sometimes, battles will occur - in these situations, you'll be locked in an arena and must battle all your enemies before you can move on. Battling is a simple affair - you can use one button for standard attacks (charge it for a more powerful one), and another button for light attacks that push enemies away. If your fellow turtles are with you, you can also hold down your character swap button for a tandem co-op attack. Some levels will allow you to play as the Nightwatcher - he fights similarly to the Turtles, except that as the more he fights, the more his 'rage' builds, which can cause a devastating surrounding attack when fully charged. The Wii version of the game controls similarly to all other versions, except that gestures are used for attacking instead of button presses.

The basic goal for each level is to get to the end. At the end of each level, you're graded on the following attributes: your speed, your combat, and the amount of coins collected. In levels where you work with your brothers, you'll also be graded on how well you worked together. Succeed in a these attributes, and you'll earn turtle coins which can be used to purchase unlockables. If you get an A Rank or higher in a level, you'll also unlock a Challenge Map, which can be played to earn even more turtle coins. Finally, once you've played any level at least once, turtle coins will appear in hard-to-reach spots for you to collect.