The first Pain was pricey ($9.99 USD) for a game that included only one level, but its simple premise proved entertaining for a brief time. Its expansion, Pain: Amusement Park, is cheaper ($5.99 USD), but it too contains a limited amount of material. Unless you were madly in love with the original game, you'll want to take a pass on this add-on.
Shockingly, Pain: Amusement Park takes place in an amusement park. Your goal is to launch people out of a slingshot and inflict as much pain on them as possible by guiding them into rides, costumed employees, exploding barrels, or whatever else looks like it might hurt. You can strike a number of poses while in midair and even use your "ooch" ability to scoot along the ground by pressing the D pad in the desired direction. Every time you hurt yourself or smash into an object and damage or destroy it, you'll earn points, which aren't really good for anything other than personal satisfaction since the game only has online leaderboards for some of the modes.
Although it can be amusing to cause mayhem, break things, and discover the paths of destruction required to score maximum points, the fun doesn't last very long. You're able to launch from only one preset point (the game gives you no clue that you can unlock a slightly different spot if you pull three hidden switches), so it won't be long before you've seen everything there is to see. You'll also need to be forgiving if you're to look past the terrible camera that is zoomed in too close when you're on the ground. Toss in erratic "ooch" controls and it's a crapshoot as to where you're going to end up once you make first contact with a solid object.
There are two additional single-player modes: one in which you grab a clown in midair and fling him into exploding barrels, and another in which you play "hot and cold" by trying to find a particular teddy bear. They don't add any significant entertainment value. A few multiplayer modes let you compete locally with up to three other players. You can bet on whether or not your opponents will hit targets that you set or try to match each other's injuries. The expansion's only intriguing addition is the Painlab. It's an experimental area in which the developer can create new environments on a planned, weekly basis. The current area isn't much more than a few brick walls and exploding objects, but the potential for some interesting concepts exists.
Pain: Amusement Park's biggest problem is that it's not a very good value. You get one level, plus the Painlab, and that's about it. The amusement park's design isn't particularly good and doesn't have the depth of the downtown level from the original release. To top it all off, additional characters are still available only for a fee, which is almost criminal considering how much you're already paying for such limited content. If you already own Pain and are craving more, this expansion may be worth a look, but its appeal is extremely limited.