If I asked you to spend the six hours between midnight and dawn attending a participatory, promenade reinterpretation of a Greek myth, many of you would find an excuse not to. Admittedly, Hotel Medea is a challenge to your commitment as an audience member, but a challenge infinitely worth undertaking, and immensely rewarding once you do.Presenting the story of Jason and Medea from its Argonautical origins through to its grisly conclusion, this production (I can't call it a play) takes you by the hand (that's not a metaphor) as you dance, run, hide, and only occasionally just watch, your way through its theatrical marathon. Unlike lesser creations which gesture weakly towards audience interaction for a bit then and then stop, your participation in Hotel Medea - facilitated by the chameleonic ensemble of maids, soldiers and attendants - is absolutely central to its meaning. When the protagonists' relationship collapses it's harrowing because you helped marry them. In the finale you become one of Medea's children, along with your brothers and sisters in the audience. Her tortured decision to kill you (with optional kiss of death for the intrepid) is all the more horrific because she tucked you lovingly into bed just two hours before. The production is bursting with well-designed moments like this, and not a single participatory element feels out-of-place or arbitrary.In case you were wondering, I'm going to town on the second person pronoun because the production's effect is an intensely personal one. The company's treatment and modernisation of Greek tragedy is very intelligent etc. etc., but intellectualising the production's effect feels thoroughly beside the point. It is to be lived and felt rather than thought about, as its emphasis on engaging as many of your senses as possible makes clear. On a more practical and less effusive note, all the moving you'll be doing can result in the unintended sensation of being very hot: Hotel Medea doesn't have a dress code, but the happiest guests were those in t-shirts and shorts.The £29.50 price-tag might be a sticking-point for some, but if you love powerful, experimental theatre you should suck it up and go. Also bear in mind that per-hour this is actually cheaper than many fringe shows, and includes frequent refreshment and even breakfast. Sublet your lodgings to a backpacker for the night (you won't be there) and you may even make a profit.The dedication required of the cast of an event like this is almost unbelievable – be it seamlessly coaxing a sometimes-reluctant audience into action, or literally baring all (consider yourself warned) in pursuit of absolute intimacy, they spend six hours unshakeably in character, reacting to whatever unexpected things their audience do. Your most affecting moments from Hotel Medea will probably come from an individual interaction with one of them – the time that Jason shakes your hand, or your maid reads you a bedtime story. The uniqueness of each person's experience makes Hotel Medea impossible to convey in complete detail, but I will be extremely surprised if some part of this show doesn't end up featuring as your stand-out memory of this year's festival.