If you travel to the Mall of America- and you have kids- it is a safe bet that you will spend some time in Nickelodeon Universe.
It's great fun as there are more rides than you can imagine in an indoor amusement park (the roller coasters- yes that's plural- have larger drops than you expect) but bring your wallet: It's expensive!
That being said, your kids will have a wonderful time flitting from ride to ride, meeting their favorite Nickelodeon characters and absorbing all the activity.
If you have younger kids (under 5) a few rides will probably soothe them and you can move on to free activities, like LegoLand, right next to the park. For older kids I suggest an unlimited ride wristband. There's also an arcade for those teens that are "too cool" for the rides.