Yulaw (Jet Li) is a renegade travelling through the parallel dimensions of the 'multiverse' to systematically bump off all but one of his alternate incarnations. If he can eliminate Gabe (also Li) then it will signal either his rise to godly status or the destruction of each universe - either way, not good.
It's ridiculous stuff, but a great excuse for director Wong to let rip with loud and brash action, while Li gets to leap, kick, punch and glare his way through most of the movie. Matrix-esque sequences ensure an arcade game feel and the acting is on a similar par, with Jason Statham employing a farcical American accent.
It's a mixed bag but, with The Rock reportedly once in the frame for the title role, the mind boggles at how awful this might have been.