Long before what is known today as "melodic hardcore," there were a precious few bands playing a new kind of punk music, at the time known as "post-punk." Bands like Embrace, Saccharine Trust, the Minutemen, and, of course, Hüsker Dü. Here is a band that took basic hardcore punk and expanded upon it, much in the same way that bands like Flipper and Black Flag were experimenting with heavier, slower tempos at the time. Hüsker Dü experimented with melodic playing and occasionally poppy song structures barraged at all sides by vicious hardcore. Their 1983 album Metal Circus sounds almost like an exact bridge between hardcore punk and "post-punk." They hadn't quite yet moved onto their equally brilliant, exclusively melodic period yet, but this wasn't straight-up hardcore either.
Songs like "Deadly Skies" (which sounds to me like it's about nuclear war), "Lifeline" and "Real World" reveal the band's obvious roots in Black Flag-influenced hardcore punk, while latter tracks like "It's Not Funny Anymore" and "Diane" bring about a whole new, very melodic sound, unheard of at the time. Another standout track is the absolutely maniacal "Out On A Limb," which features some psychotic guitar playing reminscent of Greg Ginn's short-lived band Gone.
This (along with their masterpiece Zen Arcade) are vital purchases for anyone with any marginal interest in the evolution of hardcore. Fans of relatively newer bands like Hot Water Music must hear this in order to understand where that band got its sound. I'm not sure if this album is still officially in print, but it should be easily availible on eBay.