If you took one of Tove Jansson’s Moomins, sprayed them with custard, added a third eye and stretched their ears then you might end up with Beegu. The yellow alien from Alexis Deacon’s popular picture book now crash-lands in a comical show for children aged three to seven. Director Debbie Hannan’s adaptation often forgoes the contemplative grace of the original and whips the audience into chants for the befuddled, far-from-home heroine. Bee-gu! Bee-gu!

The themes of curiosity, care and found family remain intact. A cuddly looking Beegu (movement and puppetry direction from Laura Cubitt) is principally controlled by Emma MacLennan, who also voices the alien’s inquisitive chatter. During her odyssey on Earth, Beegu is ignored and insulted by busy grownups (“bit early for a Halloween costume,” sneers one) but warmly welcomed by some friendly schoolchildren. On the Unicorn’s main stage you might think this would lead to some extravagant circus skills but their games, rendered in slow motion, instead have a simplicity that young audiences will recognise from their own playground. The same goes for the cheerleading routine that involves a litter of fluffy puppies whizzing through the air.

There is amiable audience interaction from three other performers, Lucy Havard, Lawrence Hodgson-Mullings and Aryana Ramkhalawon, who rattle through a range of supporting roles. The use of Teletubbies-style sun and moon characters, with projected faces, emphasises the message about looking out for one another but their rather solemn narrative is often superfluous. With a skyline of swerving apartment blocks on wheels, Jean Chan’s designs honour the spareness of the book. Chan and lighting designer Will Monks deliver a luminous scene in which Beegu plays music on the playground’s railings, wonderfully accompanied by Deanna H Choi’s compositions. The withering teacher wearing cat-eye glasses becomes a 10ft tall terror.

Beegu is principally an observer (despite all that chatter, she has no visible mouth) and puppet designer Jonathan Saville has done well to make her this sympathetic. At 50 minutes, the story never feels drawn out and Beegu’s meet and greet session with the audience proves the book’s point that children have a gift for forming friendships.

• At the Unicorn theatre, London, until 4 May.