Dance Dance Revolution Hottest Party 2 was announced by Konami on May 15, 2008 as part of the 10th anniversary of Dance Dance Revolution celebration. Hottest Party 2 features the same gameplay as the first Hottest Party and introduces new gameplay modes, gimmicks, characters and graphical enhancements. The game also features an all new soundtrack featuring licensed music from the past four decades as well as new Konami Originals.
Gameplay remains relatively unchanged from the original game. New modes on Hottest Party 2 include a new battle mode and the "Groove Arena", an updated version of Groove Circuit from the previous version. New additional arrow gimmicks include arrows that rebound when hit and must be hit three times in order for them to fully disappear, arrows that only appear suddenly, missiles, and an implementation of holds for the hand markers.
Source: Wikipedia, "Dance Dance Revolution Hottest Party 2", available under the CC-BY-SA License.