I bought this randomly in a Virgin megastore based solely on the blurb on the back (this was when DVDs were 15 quid a chuck) and I loved it. Six strangers wake up imprisoned in a cube-shaped room, with no memory of getting there, and clearly have to escape (ostensibly before they starve or dehydrate). They eventually realise that their prison contains many such rooms and that they can traverse between them, but some rooms contain imaginative traps. It transpires that each of the strangers can contribute something unique to the group's escape attempt (I'd love to say more, but I'd spoil it)...

This film is quite unique in that it could take place a hundred years in the past or a hundred in the future - there are no clues whatsoever in this respect. I will say that the cube is the only location used, which also removes the notion of place. This has the added effect of leaving the actors as the sole focus, so it's lucky they're good ones (including Nicole DeBoer as a haughty maths student, and the brilliant and underrated David Hewlett as a squirming engineer/scientist who may have some connection to the cube itself).

This is the archetypal "locked room mystery"; while watching Saw II I was heavily reminded of Cube. It would have made a brilliant novel, and makes a unique and watchable film. I should add that the DVD commentary is outstanding as well :).