is a musical style that evolved out of Hard House and is known in the UK as Nu-NRG. Keeping the 4/4 beat (often with Techno
-esque drum samples) and simple, often four-note melodies it has gained a lot
of popularity with both the Hard House
and Old-school Techno
crowd, especially in the South-eastern US.
What I find particularly interesting about this style is that it completes the circle in Mainstream electronic music -- In the beginning there was Techno, a hard style with focused and full-on melodies, followed by Acid house, which introduced more psychadelic melodies and a less hardcore beat. From this (especially in the US) people turned to Trance, which focused on melodies (still simplistic and made of the major chords, but longer and more subtle in parts) and put the drums in the background.
Most partykids in the (southeast) eventually moved on to Hard House, which again put the drums before the melodies but kept parts of Trance's melodic style - maybe a tad shortened, but still streching over several bars.
Hard NRG, then, falls halfway between Hard House and Techno - with its one-bar melodies and hard samples, some tracks are even more appropriately associated with the Techno genre.
Better-known DJs who spin this style include:
Kristian & Oz
RR Fierce (RIP)
Two Record Labels that specialise in this style are Lotek Records and Wasa-B Records.