In 2015, amid their tour commemorating the 30th anniversary of debut album When Dream and Day Unite, prog-metal pioneers Dream Theater—whose intricate compositions featuring John Petrucci's and Jordan Rudess's virtuosic solos defined the genre—made their debut at Wacken Open Air, the world's largest metal festival in Germany's Wacken, offering a stark contrast to the thrash and black metal-heavy lineup. The July 31 performance, later issued in 2022 as part of the Lost Not Forgotten Archives series, spanned about an hour with a retrospective focus: from the aggressive opener "Afterlife" to the epic "Metropolis Pt. 1: The Miracle and the Sleeper" and poignant "The Spirit Carries On," wrapping with "Bridges in the Sky" amid cheers from an 80,000-strong crowd, highlighting the band's shift toward heavier tones post drummer Mike Mangini's integration. Fans on Reddit and Prog Magazine reviewers extolled the show for its "unbridled energy" and audience rapport, deeming it a harbinger of the ensemble's evolution, though some critiqued the lack of improvisations in a festival setting; this gig bolstered Dream Theater's repute as progressive metal maestros captivating even extreme metal environs.