ROUNDELAY is Alan Ayckbourn's 78th play and his 79th, 80th, 81st and 82nd play too. Sort of.

To mark his 75th birthday year, he has written five short, interconnected plays that can be played in any order, some with shared characters or overlapping narratives, some that are sequels or preludes of others.

The order is decided by five audience members each picking out a title around half an hour before each performance, at which point the cast is informed of the configuration. Writer/director Ayckbourn would like this deadline to become even closer to the starting time, the more his cast and crew becomes familiar with the requirements.

Originally, it was calculated there were 120 possibilities as to the order, but already two nights have followed the same pattern. Nevertheless, the air of unpredictability that surrounds each show is another Ayckbourn innovation to add to the likes of House and Garden, where two plays are performed simultaneously in different auditoria, and Intimate Exchanges, a series of eight plays, each with two potential endings.

Roundelay is in some ways an extension of last summer's Farcicals, a brace of interlinked Ayckbourn lunchtime theatre shows, individually called Chloe With Love and The Kidderminster Affair, that could be seen separately in the bar or together in the McCarthy.

You are not afforded that possibility with Roundelay, instead seeing all five in a three-hour production in the Round.

The intention must be that they should have a greater accumulative impact, the more the plays stack up, especially given the breadth of subjects they cover, but they are not substantial works by Ayckbourn's remarkable standards.

This is partly because Roundelay is as much about style as it is about content. He calls the plays "a confectionery assortment", each with differing colours and flavours, each being given a colour code for Michael Holt's set and costume designs that includes the T-shirts worn by the crew as they move the furniture into place for each play. Those T-shirts also carry the name of each play to denote which is coming next.

Black, for example, is the colour (or technically shade, before pedants write in) for a gothic horror tale, The Novelist, while blue is chosen for The Politician, the story of misbehaving Tory Leo Axminster (Nigel Hastings) in a farce that echoes Rik Mayall's Alan B'Stard.

On press night, the order wasThe Judge (colour, red), The Novelist and The Politician in the first half; The Star (yellow) and The Agent in the second. That meant Russell Dixon's cantankerous old judge, Tom, appeared in the first two, one a study of fading and failing memories, the other a throwback to Tales Of The Unexpected, which for all their differences, somewhat deadened the impact of the random order.

A judge and an agency girl (Brooke Kinsella); a deceitful politician and a call girl; a wannbe theatre starlet (Krystle Hylton) and an agent (Sophie Roberts); a spinster novelist (Alexandra Mathie); a thug collecting debts(Leigh Symonds); a vicar (the outstanding Richard Stacey) at odds with his faith; all manner of life is here and plenty of shards of laughter too. However, five plays don't add up to one of Ayckbourn's best plays.

Roundelay, Stephen Joseph Theatre, Scarborough, until October 4. Box office: 01723 370541 or sjt.uk.com