A hilarious gem of a game that takes unilateral advantage of the Havok engine.
The premise is quite simple. Put a guy in a slingshot and hurl him against as many things as possible, causing a truck-load of destruction while inflicting cringe-inducing pain on the unfortunate victim being catapulted. You can play an assortment of mini-games that make use of this premise--for instance, trying to hit monkeys, explosives, mimes, or just basically racking up a whole lot of points.
When I first downloaded PAIN, it was disappointing just to find only one level to mess around with. Recently, they added a new Amusement Park that I have yet to download. In addition, you can also purchase new characters for 99 cents each. It might have been better if you could just go through the trouble of unlocking them for free--it would have added incredibly to the replay value.
This isn't just a fun video game for the PSN--it's also a great stress-reliever. Whenever you're having a really bad day and you want to take it out on someone, there are few games like PAIN that give you that satisfaction.