The goal is for you to win more categories than your opponent, and you'll have 7 tries to do this.
Once the game starts, you'll see two towers, one will belong to your opponent and the other will belong to you. In the lower part of the screen, you'll see six boxes that represent each of the game's categories: History, Science, Geography, Art, Entertainment and Sports.
To compete for a category, you'll have to press on their respective boxes. Once you do that, you'll receive questions, and you'll have to try to answer as many as you can correctly and consecutively. If you get more right answers than your opponent, you'll win the character of that category and it will join your tower. If you don't answer correctly, you'll lose a life and you'll break your streak.
The player that wins more categories, will win the game. You will win a category when you get more correct answers than your opponent.
Keep in mind that you'll be able to use your tries as many times as you want in each category, which means that even if you earn a character, your opponent will be able to play in the same category to try to take it away from you.
If there's a tie in the number of characters each player wins, the player with the most right answers will win.
If you want to play Tower Duel with a teammate, we recommend you visit the following article: How can I play Tower Duel with my teammates?