What to do after reviving the 1980s? How about resurrecting the 1990s?
That's one way to look at U2's recently launched Experience + Innocence tour, which the veteran Irish band brought to the Forum on Tuesday night for the first of two dates.
Ostensibly designed to support U2's 2017 album, "Songs of Experience," the new road show follows the group's stadium tour last year marking the 30th anniversary of its landmark "The Joshua Tree," which came out in 1987.
It's that throwback impulse that still seemed to be driving U2 at the Forum — only this time, with a different decade (and a different attitude) in mind.
The concert featured a long section in which Bono, wearing whiteface and a top hat, performed as MacPhisto, the devilish alter ego he devised for U2's early '90s Zoo TV tour.
There was a comic book-style video interlude set to a recording of "Hold Me, Thrill Me, Kiss Me, Kill Me" — the band's contribution to the soundtrack for 1995's "Batman Forever" — sung by Gavin Friday and Arcade Fire's Régine Chassagne.
And the show had an overall world-weary vibe that felt in keeping with U2's "Achtung Baby," even as the group sought to refresh its concept of mass-media fatigue for the iPhone era.
Addressing the audience before he sang "One," Bono urged people to take part in a certain social-media initiative, then appeared to lose track of which hashtag he'd meant to promote.
"So many hashtags in my life," he said with a knowing chuckle.
U2 peppered the concert with other references to now-current events, including images of the Charlottesville, Va., tiki-torch mob that flashed on giant screens during "Staring at the Sun." (Bono introduced that tune, from 1997's "Pop," as one about "political blindness — the kind that can tear up a home or a nation.")
During "Acrobat," a song from "Achtung Baby" that U2 began playing live just this year, Bono-as-MacPhisto did a few lines from the Rolling Stones' "Sympathy for the Devil," but tweaked the words to evoke Donald Trump: "I made damn sure the president's hands were full of stormy weather."
However up-to-date the details, though, the larger idea that U2 was putting across — that a world-famous rock band should engage directly with the politics of the day — registered as a remnant from before the turn of the millennium.
Since 2000, rock has given way at the center of the conversation to other forms; now hip-hop, with all its outrage and hedonism, is the voice of popular culture.
And many of the rockers that remain have turned inward — think of Bob Dylan's journey through the Great American Songbook or Bruce Springsteen's deeply personal Broadway show.
U2 has done that too. "Songs of Innocence," its 2014 album, looked back in detail at Bono's childhood and at the band's beginnings in Dublin.
The group played some of those songs Tuesday — including "Raised by Wolves," about a terrorist car bombing, and "Iris (Hold Me Close)," titled after Bono's mother, who died when he was 14 — in arrangements held over from U2's 2015 tour behind that record.
As on the earlier trek, the group performed on two stages connected by a narrow walkway that allowed the musicians to walk between those huge video screens, which the audience could see through. The effect in "Cedarwood Road," about the street where Bono grew up, was that the singer looked like he was standing in front of his old house.
Yet "Songs of Experience" reset the band's view on the outside world — and, in that way, marked a return to U2's old-fashioned belief in its own importance.
Could the group convince anyone else that it still matters? Occasionally.
"The Blackout," a cut from the new album in which Bono worries that "democracy is flat on its back," was punchy and loud; it carried an urgency that lived up to the memory of those earlier days, when fans were hanging on the singer's every word.
And among the oldies U2 played, "Pride (In the Name of Love)" inspired a palpable surge in the crowd as the Edge's guitar line ricocheted through the arena and the screens flashed images of the Rev. Martin Luther King Jr. — reliable liberal chum for an audience hungrier than ever for it.
At other points, though, U2 wasn't doing enough real-time work to transcend easy nostalgia.
"Until the End of the World" had the bleary textures of "Achtung Baby" but lacked the album's anxious propulsion, while "City of Blinding Lights" delivered far less energy than its title promised.
And too many of the group's dim-witted new songs — "American Soul," "Love Is All We Have Left," you get the picture — deployed the language of classic U2 without any of the intellect that once defined the band.
You could understand, of course, why the group had its heart (if not always its head) in the '90s: Back then, U2 was popular enough that it could withstand the blowback to the experimental "Pop."
Two decades later, though, it's no longer clear that the world needs U2.
This show didn't quite make the case.