And while some of the in-movie puzzles are relatively obvious (hell, they even borrow one from Jim Henson's Labyrinth!), the movie as a whole proves to be sort of a puzzle in its own right.
Gimmicky but gripping, at least in its first half, this Spanish effort is a deathtrap thriller with maths puzzles, strongly reminiscent of Vincenzo Natali’s way-superior Cube or a special edition of The Crystal Maze.
Poppy Wood, Mike McGrath, Benedict Smith, Luke Edwards, Steve Bird, Tim Robey•The Telegraph•May 29, 2009