It was a movie where a bunch of people bring one guest to a party where they drug them and the guests end up in an arena with collars thar have like acid in them. It is till the death and they have to make it through obstacles to live while the original team is betting on the survivor. I remember there was a part they went through a maze of light and dark but the light spots can kill you. At one point two kind of fall in love and kiss and he sacrifices himself so she will win. When she dies she begins part of their team and starts to bet on the game until she starts running it. The end is when she puts the original gang in the game with a short timer where the collars kill them all and I am assuming who ever really runs these picks her up.