What's the movie?

Okay this is a movie i've been recalling everyday but i never remember the name of it and it bugs the hell out of me..

So this is what i remember happening: there's people, obviously, that have been kidnapped by someone and they're thrown into this house, or room? and the only way to get out of this room is by being the only one left, which means, they have to kill eachother. I remember they get, like, a small portion of potatoes as their meal, and that one of them falls from a staircase? and dies, and i remember too that in the end, the winner got a bag full of money and takes the elevator to freedom.

I watched this movie like six years ago and i know for a fact that it's not one of the Saw movies. I really hope on of u reading this knows what movie i'm talking about, thank u in advance :)