The Last Empress, Hammersmith Apollo, London<br></br>Titus Andronicus, Riverside Studios, London

Who'd be an empress if this is how you're remembered?

Not so much The Last Empress as The Final Straw, a reportedly magnificent, Oriental epic musical has arrived in London. That such a stupendous fiasco can have enjoyed two sell-out runs at New York's prestigious Lincoln Center beggars belief. Swerving between recondite and appallingly calculated "accessible" ingredients, this is cross-culturalism at its most risible.

Certainly, as the first musical from the Far East to reach Broadway, it is ambitious and could have been intriguing. Korean writer Mun Yol Yi's sung-through saga focuses on Min, formidably pioneering queen of the Chosun dynasty. In the late 19th century, she compelled the regent, Taewongun, to retire and her young husband, Kojong, to open up the Hermit Kingdom to Western influences. She survived one coup but was assassinated in a Japanese samurai-led slaughter. Chogun posthumously honoured her with the title of Empress.

Unfortunately, you'd barely decipher any of this from director Ho Jin Yun's staging which, while offering some top Asian singers and spectacular robes and crowns, is garbled on a grand scale. In Kojong's needlessly revolving throne room, confused hoards of marauders rush to and fro, halting for stave-brandishing interludial stomps that are never genuinely fearsome. There's a bewildering lack of distinction between the European allies and the Japanese. The cast, singing in English, are almost wholly unintelligible as well. When occasionally the orchestra stops drowning them out, you realise that the lyrics are utterly banal (as translated by Georgina St George). Kojong's operatic lament bathetically descends to, "I miss my wife," while a po-faced Taewongun intones, "Under the circumstances, son/ I think it's time that we moved on."

On the subject of progress, this show is peculiarly muddled. As far as I could make out, Tae Won Yi portrays Min as a noble heroine with no down-side. In this production (sponsored by the Korean Ministry of Culture and Tourism) she's admired for her vision of a multicultural future. Yet, jarring with that, other players caricature malign, invasive foreigners. Meanwhile, I wished Hee Gap Kim's score were less Westernised. Sometimes he gives us haunting pentatonic melodies, but mostly they're subsumed by a gushy classic string section and what sound like tributes to Andrew Lloyd Webber and vintage Broadway (plus faintly silly echoes of Gilbert and Sullivan). That Taewongun, the fierce isolationist, shares a taste in tunes with Cameron Mackintosh seems most perverse and Min's finale – rousing her people to "run from yesterday" – preaches a lesson her nostalgic biographers have not taken to heart.

Perhaps from the Korean perspective, the fusion of musical styles appears more exciting or even full of Occidental promise. However in London, where Sir Andrew himself has declared the mega-budget musical outdated, you can't help thinking the sooner The Last Empress is theatre history the better.

A few yards down the road but metaphorically streets ahead, there's another bloodbath – this one springing from Imperial Rome's wars against the Goths. Working with a relatively microscopic budget and a busily role-swopping cast of eight, Kaos T.C.'s take on Shakespeare's notoriously gory Titus Andronicus is experimental and extraordinarily harrowing. Xavier Leret's production is set on a narrow strip of white tiles with clanging steel doors, suggesting some nightmarish modern slaughter house. The tension slackens at points and Ralf Higgins and Jack Corcoran owe too much to Steven Berkoff, playing the avenging sons of the captured Goth queen Tamora as grotesque yob-clowns in tracksuit bottoms. Yet Leret's wayward ludicrous touches – including a Basil Brush puppet in the hunting scene which precedes the worst horrors – are oddly in touch with this play's delirious sense of black comedy. There's also clear contemporary relevance in this portrait of harshly treated prisoners of war and tit-for-tat killings (which will surely provoke thought when Kaos tour to Israel).

Crucially too, this ensemble's mood can switch in an instant – supported by strangely fitting background music that ranges from funk to a quietly melancholy church organ. Lea Beagley, as the increasingly broken General Andronicus, speaks verse with an effortless clarity worthy of the RSC. By his side Jane Hartley, embodying his raped and mutilated daughter Lavinia, is acutely distressing – just struggling to keep breathing. Unforgettable.

k.bassett@independent.co.uk

'The Last Empress': Hammersmith Apollo, London W6 (0870 606 3400) to Sat; 'Titus Andronicus': Riverside, London W6 (020 8237 1111), to 23 February