Though they were likely lost on casual hip-hop fans, Southernplayalisticadillacmuzik was full of subtle indications that OutKast were a lot more inventive than your average Southern playas. Their idiosyncrasies bubbled to the surface on their sophomore effort, ATLiens, an album of spacy sci-fi funk performed on live instruments. Largely abandoning the hard-partying playa characters of their debut, Dre and Big Boi develop a startlingly fresh, original sound to go along with their futuristic new personas. George Clinton's space obsessions might seem to make P-Funk obvious musical source material, but ATLiens ignores the hard funk in favor of a smooth, laid-back vibe that perfectly suits the duo's sense of melody. The album's chief musical foundation is still soul, especially the early-'70s variety, but other influences begin to pop up as well. Some tracks have a spiritual, almost gospel feel (though only in tone, not lyrical content), and the Organized Noize production team frequently employs the spacious mixes and echo effects of dub reggae in creating the album's alien soundscapes. In addition to the striking musical leap forward, Dre and Big Boi continue to grow as rappers; their flows are getting more tongue-twistingly complex, and their lyrics more free-associative. Despite a couple of overly sleepy moments during the second half, ATLiens is overall a smashing success thanks to its highly distinctive style, and stands as probably OutKast's most focused work (though it isn't as wildly varied as subsequent efforts). The album may have alienated (pun recognized, but not intended) the more conservative wing of the group's fans, but it broke new ground for Southern hip-hop and marked OutKast as one of the most creatively restless and ambitious hip-hop groups of the '90s.