King René's Tournament Book is a fancy book from a king who lived a long time ago in a place called France. The book is full of colorful pictures and stories about knights and fancy events called tournaments.
You know how sometimes you play games with your friends like tag or hide and seek? Well, back then, knights played games too, except they were much more fancy and had a lot of rules. They would ride on their horses and try to hit each other with long sticks called lances. The tournaments were like big parties where knights from all over the land would come to show off their skills and win prizes.
King René was really interested in these tournaments and wrote down everything he saw and learned about them. He even made really pretty drawings to go along with his stories. His Tournament Book is special because it's one of the oldest and most detailed books about tournaments that we still have today.
So, basically, King René's Tournament Book is a book full of pictures and stories about knights and fancy tournaments. It's cool because it tells us about a game that people played a long time ago, and we can still learn from it today.