KÀ is Cirque du Soleil's bold interpretation of live martial-arts period fantasies like Crouching Tiger, Hidden Dragon in the adventures of two separated twins. The $165 million opus includes huge puppets and a battle on a vertical wall. A fixed stage is replaced by an 80,000-pound deck that's maneuvered by a giant gantry arm into all sorts of positions, including vertical. Though no Cirque that followed rivals it for sheer spectacle, the operatic tone remains divisive; those not sitting close enough to see faces can be confused by the story, which is told without dialogue. But after a decade on the Strip, it still stands as an amazing monument to the sky's-the-limit mentality that fueled Vegas in the go-go 2000s.