“The Tournament” is a big side quest that takes place in the second half of Assassin’s Creed Shadows ’ main story. It’s very rewarding, and will get you new weapons, XP, Anomaly completions for the Animus, an achievement, and a mastery unlock for Yasuke’s Kanabo and Naoe’s Tool tree:

Shadows is Ubisoft's most successful game in the franchise by a Japanese country mile, ranking high in both sales and player counts.

Ubisoft didn't originally have yellow paint in Assassin's Creed Shadows, but stupid players kept getting lost in the open world.