To ensure fair play, users are not allowed to enter a race if they've already seen even one of the questions. So after you play a "random opponent" race, our system needs to match you with someone who has not previously seen any of the questions in that race. Sometimes there is another open race that is a suitable match, and so you will see your results immediately. Other times, the system needs to wait for someone to come along who has not seen any of the questions that you played. If this doesn't happen within 7 days, your credit will be refunded. If you scroll to the bottom of a given category page, you will see open races that are waiting for opponents and which you can play for instant results.