To start a game you must press the "Play" button on your home screen and then select the "Daily Challenge" option. When you do this, a screen will be displayed in which you can see the time remaining to complete the challenge, your progress in it and the amount of crowns that you can receive as a reward if you complete it.
The mode consists in completing four streaks made up of 5, 10, 15 and 25 questions that must be answered correctly and consecutively. By completing each streak you will receive a prize in crowns that you will see increase as you progress. Your progress will be saved, and you can resume the challenge at another time from the beginning of the streak you have reached. Keep in mind that, as it consists of a daily challenge, this progress will be reset after the 24-hour period.
If you answer wrongly, you can choose to view an advertisement or pay a cost in gold bars so as not to lose your turn and continue responding.
It is important to keep in mind that when you scroll down the screen, you will find all the categories available to answer questions on specific topics. There you can choose the free categories, or unlock many more using your gold bars.