In May 2015, a group called The Social Experiment released for free its surprise debut, Surf, a minor major-key miracle that gathered gospel singers and spoken-word champs, Chicago undergrounders and everywhere-else above-grounders (Big Sean, Erykah Badu, Busta Rhymes, Janelle Monae), under a big-top tent emceed by a horn-blowing Horatio named Donnie Trumpet. The Social Experiment's uncredited Hamlet and actual MC is Chancellor Bennett, an early-20s talent font who first got traction in 2012-13 with two wildly assured mixtape giveaways, 10 Day and Acid Rap. By the time he dropped his third one, Coloring Book, in May, Chance the Rapper was an above-the-fold headliner and hip-hop household name, the honored guest on Kanye West's The Life of Pablo, on which he foreshadowed the game change he would foment three months later ("Let's do a good-ass job with Chance 3/ I hear you gotta sell it to snatch the Grammy"). He was at least half right: Coloring Book is a watershed album, an all-in move on Pablo's half-measured gospel rap and a chart attack by Surf's experimental melting pot — the first not-for-sale LP ever to hit Billboard's Top 200 off streaming pittances alone (57 million plays roughly equals 38,000 units, good for eighth place its first week). "Am I the only one who still cares about mixtapes?" wonders one of its hundreds of hooks. He already has an answer. Francis and the Lights opens.