If you’re looking to be led though some sort of polished, well-rehearsed routine by a barely-ruffled purveyor of observational humour, you might come out of this show a tad bemused. Thankfully, Richard Hanrahan is aiming for (and attaining) the precise opposite – presenting the gathered throng in The Grassmarket Hub with perhaps the Fringe’s foremost recursive multimedia comedy nightmare.

It’s quite hard to write an accurate review of the show, given that much of the content alters from night to night – with whole new routines and video segments being produced in response to suggestions from the audience. One example sees footage of a previous attendee being prompted to answer the question “what makes you laugh?” – her eventual reply (“animals”) and elaboration (“their…paws”) then leads to an entire rathergood.com-style music video extolling the virtues of animal limbs at length. Other topics covered on the night I attended included: Stewart Lee-style audience segmentation, “just sort of going into public places and screaming ‘JOHN'” and casseroles.

Hanrahan himself is an affable bundle of nervous energy. He emerges clad in goat legs (a sartorial suggestion from a previous show) and a long-unwashed Herefordshire Junior Chess Competition jumper, which he assures us is authentic. The next hour-or-so is  filmed by at least three of four separate devices as he quizzes the crowd on their own comedic predilections, while sharing previous findings, riffing off audience-interaction and presenting the story of the run thus far. There is something Lee & Herring-esque in his surreal energy, quick-wit, love of diagrams and general comedy-as-deconstruction-of-comedy style. He is willing to go to pretty much any length for a laugh, including actual (mild) physical danger in one memorable video clip. He also possesses a winning sense of self-deprecation – humour and an odd sort of pathos can be wrung out of even the multi-angle close-up of him making an extended, desperate fart noise at a resolutely unamused person from one of the earlier shows. He’s hit on a winning formula where even catastrophic failure can be redeemed for laughs in future nights.

As well as being an exhausting undertaking for the performer (physically, emotionally and financially), the constant metamorphosis of the act is a masterstroke of guaranteeing repeat punters through the door. In order to see the payoff to some witty remark or suggestion you’ve supplied him with, you’ll just have to come back and hope you’ve made the cut. It represents unbeatable value for money – in part because it’s pay-what-you-want, so you literally value it yourself. Indeed the show continues long after you’ve left it – there’s a facebook “Support Group” where further videos are uploaded and suggestions canvassed.

Richard Hanrahan is assembling a vast, ever-shifting edifice of comedy – a Tower of Babel which may yet collapse into a terrifying incomprehensibility. A funny one, though.