They're now signed to Def Jam, but Philadelphia boho rap band The Roots don't try to fit in with the label's decidedly mainstream roster. In fact, Game Theory is their toughest, weightiest, and most uncommercial effort yet. Opening with the antiauthoritarian ''False Media,'' it's all ghetto vérité and political paranoia, with claustrophobic production to match the doom and gloom. The disc gradually turns from angry to melancholy, ending with an eight-minute tribute to the late producer J Dilla. This is the rare hip-hop release that's both gripping and touching.