How to Play a Question Game in a Class?

i like to throw this game in every once in a while with my upper level students, just to check that ther question for mats are still up to speed. It's quite good for basic bits of grammar and simple yes or no questions. The main idea is that you have were going to use the am the topic of famous people? No, we'll cho s one famous person, and then the other person needs to ask yes orno questions. And it has to be 20 questions, because not normally, when i play it, i don't bother to count. Oi rege do, but you lready know thati'm kind of a little crazy about my games. Yes?