ICELANDIC modern classical composer Olafur Arnalds is a multi-talented artist who seems to have tried his hand with most things, including drumming for metal bands and composing film scores, most famously for the ITV series Broadchurch.

His festival OPIA at the Royal Festival Hall and Queen Elizabeth Hall brings together a string of groundbreaking piano-based composers for one long night only.

One of the most compelling, Rhye, sees Canadian singer Mike Milosh team up with his track-suited pal Quincy for an entirely improvised set on two pianos, complemented by Milosh's incredible falsetto.

He sings nonsenses to the audience before asking them to suggest something he should deliver and after dismissing a few, including "hope" which is "too corny," he settles on a song about an octopus.

After delivering a highly entertaining tune on the hoof, he ropes in Quincy for a final sing-along that sees them walking the length of the auditorium. They're having as much fun as the rest of us.

Other eye-opening sets came from Poppy Ackroyd, who takes us to another plane altogether with a performance that sees her plucking the strings of her piano like a harp.

Then there's Hogni & Ensemble, who perform a special set with a string quartet, and Grandbrothers, performing with a band put together especially for OPIA.

As for Arnalds himself, there are few words to describe the epic transformation of the packed Royal Festival Hall that his music and the venue's breathtaking lighting creates.

At one point, flashing blue lights make Arnalds and his fellow collaborators on strings look as if they are shipwrecked at sea.

The group have been on tour since the release of re:member in August last year and tonight he plays a smattering from that, including the beautiful Saman.

If people aren't already getting emotional, he certainly has the audience in tears as he finishes with song Lag Fyrir Ommu, which he explains he wrote for his grandmother after she died.

Climate-conscious Arnalds has also planted a tree for everyone attending and we're given a card with a code on as we leave to view our very own tree online.

An apt gift in a climate emergency.