If your game is completely different from the film, then I doubt they’d have a case against you. It also doesn’t seem like it’s a big Hollywood production, so they likely don’t have the lawyers to even attempt it if it is not a clear case of infringement. You could call it “The Cube” and probably avoid it entirely. This sounds more like a question of Trademark law however, not copyright. And it doesn’t seem like anyone owns a trademark on “Cube”, likely because it is too generic.