Hip-hop in the 21st century so often presents as a music of excess – large crews, busy production, bling. Into the maximalist melee steps Long Beach rapper Vince Staples: tonight, a lithe cypher silhouetted against a glowing backdrop, intense to the point of abstract expressionism. He might be wearing trainers and black jeans and a T-shirt; it’s hard to tell. Non-hip-hop audiences might recognise Staples’s voice from Ascension, a standout cut from the most recent Gorillaz album, which – against the odds – actually slots into Staples’s electrifying set without friction.

Honed by festival appearances, and backlit for an entire hour or so, Staples is a masterful absence, a compelling ascetic who delivers fat-free banger after fat-free banger. There’s no support act, no hype man; there are no dancers and no pyrotechnics – just juddering electronic playback, clever lights, tightly wound kinetic energy and Staples’s deadpan, nasal California delivery, imbued with a west coast bounce that harks back to Snoop Dogg and Dr Dre but is beholden to no one.

From the first bars of Party People – lifted from his most recent album, Big Fish Theory – the entire venue is on its feet. “Party people, I like to see you dance,” runs the chorus. Despite setting off two moshpits, the song is no mindless anthem to hedonism. Rather, the verses reveal how Staples is still occasionally suicidal despite his success.

Vince Staples at the Forum. Photograph: Katherine Anne Rose/The Observer

When Staples isn’t rapping, he lets his songs play out, giving the music and the colours ample space to breathe

Staples identifies as a “Norf Norf soldier”; his gangland backstory in North Long Beach – as told on his official debut, Summertime ’06, and since – is at once chilling and heart-rending. Staples’s music, though, transcends many hip-hop cliches, and Big Fish Theory shifted Staples’s unflinching gaze away from his time as a Crip to hip-hop’s many contradictions, not to mention wider issues such as race and politics. There’s an anthem still waiting to happen in the hard-hitting BagBak. “Tell the 1% to suck a dick because we on now,” Staples yells in the chorus. “Tell the president to suck a dick because we on now.”

These newest Staples tunes borrow widely from UK rave and electronica. Stark, springy sounds come in thick and fast from left field. Big Time – off Staples’s intervening Prima Donna EP (2016) – boasts bass that rattles both hair and clothing. Its series of bloops, clanks and rattles are the production work of our own James Blake. Not long after comes Samo, and an even more abstract set of trap signifiers that squeak and tickle, the work of London pop deconstructor Sophie. Somehow, a party atmosphere holds out throughout, thanks to the rubberiness of Staples’s delivery. When Staples isn’t rapping, he lets his songs play out, often with his back to the crowd, giving the music and the colours ample space to breathe.

Many of the better-known Summertime ’06 tunes get the bigger reactions – Lift Me Up, for one, with its powerful depiction of how Staples’s “pain is never over”. There is no encore, but the set ends with the mighty Norf Norf, a barely-there tune that showcases Staples’s pitiless flow. “I ain’t never ran from nothin’ but the police,” he offers in the chorus. The song gained greater notoriety last year when a Christian woman went on a Facebook rant against it, exemplifying mainstream America’s ignorance of the realities of racism. (Typically, Staples defended her right to react as she saw fit.)

But Big Fish – the album’s (nearly) title track – supplies an onomatopoeic thrill that is nothing short of sublime. The hook is Juicy J’s, but Staples excels on the verse. He is “reminiscin’, sitting in that Benz, of the 22 bus stop way back when”. Specifically, on one of the best lines of the year, he’s looking out for anyone likely to pull a gun on him. Live, Staples’s syllables ricochet around the room, worth the ticket price alone. “With the 22, five shot eyes on scan/ For the click, clack, clap or the boop, bop, bam.”