Note: I'm assuming you have at least a little basic familiarity with music video games such as Guitar Hero and Dance Dance Revolution. Pump it Up is a fairly obscure arcade dancing game, which plays exactly like Dance Dance Revolution. If you are familiar with Dance Dance Revolution, imagine the exact same in-game interface, replacing the cardinal directions with corners and a center panel.
Once again our annual new edition of Pump it Up, the Korean arcade dancing game, has had it's 9th International release. Once again it's, well, another song bank. NX2 has the feel of a glorified stand-alone expansion pack, unlike the evolution it touts itself as. NX2 brings 28 new songs to the table, while removing a sizeable chunk of the songlist from previous iterations. Many older songs are still available exclusively within WorldMAX, NX2's campaign mode. In essence, WorldMAX features a world map in which you move from node to node clearing various challenges for unlocks. The catch is, WorldMAX is geared strongly towards the hardcore. Unless you are a veteran Pump it Up player, you'll find WorldMAX extremely difficult. The challenges tend to feature a song with alternate Crazy or Nightmare steps, with a gimmick such as a high speed modifier; items; or various methods of sending the arrows to the hit zone.
By the way, starting with NX2, all machines are 2 songs + bonus for As or better on all songs. Every single other mix beforehand was 3 songs + bonus. Unless you get an A on every stage, you're stuck at two songs for a dollar, buddy.
There's also a USB system in place which saves your stats, opens up two songs, saves your WorldMAX progress, et cetera. This would be great if you didn't have to buy a proprietary USB card to play with. They're not sold at your local arcade, in stores, or even from the official website (individually, anyway). You have to find someone who bulk ordered a bunch and pay around $25. It's not 100% horrible, though; the drive works as a standard 1GB USB flash card. (even though 4GB cards are now down to $20)
In closing, I do recommend at least one play even if you're a head captain of the DDR or ITG camp, if anything to see what's going on over at Pump HQ. Just don't expect any fireworks.