The evil Specter is attempting another plan to take over the world by broadcasting his own TV stations. The shows on the stations are so stupid that they turn everyone who watches them into a mindless couch potato. Spike, Professor, and Jimmy have been turned into mindless couch potatoes already so its up to Kei and his sister Yumi to save the world.
The game allows the player to choose between a playable male character (Kei) and a playable female character (Yumi) at the beginning of the game. The gameplay consists of basic platforming and capturing monkeys. The right stick is for aiming and swinging weapons (such as the monkey net). Players can have four items equipped at once, on the X, Square, Circle and Triangle face buttons. Unlike some platformers, Ape Escape uses the R buttons to jump.
New to the series is the ability for Kei and Yumi to morph using different costumes like a knight or a ninja to gain new abilities.
The game also includes three mini games, one of which is Mesal Gear were you get to play as Pipo Snake, a monkey with Solid Snake's DNA in him. Snake has been captured by the monkeys and it is up to Pipo snake to save snake and stop the monkey Metal Gear.
Interestingly, Metal Gear Solid 3: Snake Eater had a minigame in which Snake had to catch monkeys from Ape Escape.