Game is a very popular term in improv circles these days. It's a very useful tool for establishing and heightening the comedy of a situation, though I don't think it's the only tool. In fact, I think it's kind of like saying "Let's build ourselves a stupid house with nothing but this hammer!" You're going to need that hammer, but you probably are going to want some nails and a saw and an architect and other house building stuff. Probably a mug that says "World's #1 House Builder", too, because you gotta toot your own horn before anyone else will, amiright? Anyway, game is a very useful improv tool and is worth mastering. But if you're going to use said tool, it's important to understand what it is and what it isn't. I mean, don't be trying to cut that 2 x 4 with a hammer like some kind of Amelia-ass Bedelia fool!
Works on contingency? No! Money down!