Ape Escape is a cute 3D chase game where you basically have to collect escaped apes by hunting them down within the landscape and catching them in your net or using some other gadget to catch them. It starts off easy and gets progressively harder.
Ape Escape has a nice feel to the controls (one of the very first games to use Dual Shock twin analogue controllers), and the gameplay is varied enough to make it compulsive, once you start. So Ape Escape is generally fondly remembered by those who’ve played it.
Someone should tell the Sony marketing people, though, that apes are not monkeys… Apes and monkeys are different. But what do marketing people care?
More: Ape Escape on Wikipedia