If ever the world needed a new Bill and Ted film, now is the time. When Bill & Ted’s Excellent Adventure came out in 1989, it was an anecdote to the cynicism and greed that seemed to be dominating both American politics and cinema, which was filled with films like Wall Street. But along came Bill (Alex Winter) and Ted (Keanu Reeves), two goofy kids who travel through time to assemble historical figures for a high school history presentation.

The Valley-accented, Van Halen-worshipping doofuses were endearingly silly, and also did the world the favour of bringing the internet’s favourite boyfriend Keanu Reeves to worldwide audiences. Two years later, Bill & Ted’s Bogus Journey was released, and rumours of a third film have been swirling since 2010 – to no avail.

But as Bill & Ted Face The Music hits cinemas, it feels as though fate, as ever, had a plan for Bill and Ted all along. The film, like its predecessors, is winningly modest and delightfully daft, offering audiences some comforting nostalgia, light-heartedness, and sunny, huge-hearted characters – just what we all need right now.

Reeves says he’s honoured to bring out another Bill & Ted film, as they’ve always had an inherent sweetness and a theme of inclusivity and people coming together and being kind.

“The idea of being kind to each other is a very good one and has more impact now,” he reflects. “Due to the situation we find ourselves in, I think being excellent to each other is a very good idea.”

For Alex Winter, Bill & Ted Face The Music is also a moving film right now as it addresses two characters facing overwhelming challenges but working through them, together.

“It’s been many years since we’ve seen them last,” says Winter, “and during those years they’ve lived lives and got more mature relationships with their daughters and their wives, and even with their friendship – and that’s tied together with the pressure of this destiny that they’ve been given to unite the world with music, which they haven’t been able to do. We’re examining what that maturity and pressure look like. So it’s been interesting to meet them now in the present so we feel the weight of these guys, as well as their joy and lightness and spirit.”

Though Bill & Ted will always have a huge nostalgic element, the film does try to show how the characters have grown over time, even down to how their guitar-shredding metal band, Wyld Stallyns, has evolved – thanks to the musical taste and talents of their daughters.

“The writers did that with the structure of the film and the plot, which is all about facing the music and being in the moment,” Keanu notes.

Even Bill and Ted’s beloved music tastes have evolved – Big Black Delta, Lamb Of God, Mastodon and Cold War Kids are among those gracing the soundtrack – showing how they’ve remained open and curious over the years instead of getting stuck in the past.

“One of the opening scenes is a wedding ceremony, and Bill and Ted aren’t there playing their Van Halen riffs, they’ve expanded their musical excellence!” he laughs. “They’ve moved on and developed, and even the theme of the daughters using music as mash-up construction is a very modern idea and I think that brings it to the present day.”

Fatherhood has clearly changed Bill and Ted, and again the film shows the two easy-going men facing gigantic challenges on levels both cosmic and personal. Not only have they not succeeded in writing the song that will save the world, but they’re also struggling to maintain their relationships with their families, even entering marriage counselling and experiencing some friction with their daughters, played by Samara Weaving and Brigette Lundy-Paine. But unlike the surprisingly dark domestic life portrayed in the original, in which Ted’s father is an angry, belittling drunk, and Bill’s old man no better, it’s clear that Bill and Ted are, as ever, well-intentioned and really trying their best. This grounded foundation not only fleshes out the characters somewhat but also serves as a nicely realistic starting point from which to jump into the fantastical world of Bill and Ted’s adventure.

Winter appreciated getting to revisit these characters at a later, more complex time in their lives. He also says that Bill and Ted’s gentleness was always in contrast to their fathers’ cruelties, and their idea of being a good man is rooted not in toughness or aggression, but kindness.

“It’s fun to play with Bill and Ted as dads,” says Winter, who has three children himself. “It changes you, in terms of how you approach the roles. We never felt that Bill and Ted were bro-y, they’re more childlike than they are bros, but once you’re a parent it changes you and Bill and Ted really love being dads and husbands.”

The duo’s adventures also become more personal as they’re confronted with different versions of themselves throughout time, including evil robot iterations and prison yard Bill and Teds. Reeves says he hopes the audience enjoys getting to know the characters by seeing them in these other potential realities, and that the emotion and humour still comes through.

“It’s nice to play this kind of darkness against the lightness of them,” he reflects, and Winter agrees: “That’s new and something we didn’t do before in the other two movies, but this is really just Bill and Ted in very painful, traumatic periods of different iterations of their lives, and there’s a lot of comic potential there but also more emotional potential.”

The introduction of Bill and Ted’s wives and daughters adds some interesting female characters to their world, which had previously been missing from the other films. The daughters play a vital part in their dads’ new mission, travelling through time to try and assemble the greatest backing band ever, which is the cue for some convincing Mozart, Louis Armstrong and Jimi Hendrix lookalikes. Elsewhere, we get to see the real Kid Cudi, Dave Grohl, Win Butler and Weird Al Yankovic, but sometimes for mere seconds.

Reeves was delighted to work with Samara Weaving who plays Bill’s daughter, and Brigette Lundy-Paine who cops for Ted.

“Samara and Brigette are such lovely people, and really talented, and they brought an enthusiasm and fun and added to the experience,” he beams.

Coming out 31 years after the original, Bill & Ted will now be seen by audiences who weren’t even born when the original came out, introducing a whole new generation to these softhearted airheads.

“We’ve experienced something akin to that already,” says Reeves, “meeting people who have met us and been really excited, and then are telling us that they’ve shown the films to their kids, and then we’ve met those kids, which has been lovely. Hopefully those who see this one will enjoy it, too.”

As for what advice Bill and Ted, those beacons of hope, slayers of evil, bringers of rock, would give to modern audiences, nothing has changed.

“Be excellent to each other”, grins Reeves, “and party on, dudes.”

• Bill & Ted Face The Music is in cinemas now.