While most of the realm is happy to partake in viewing jousts and combat tournaments, a new sport has arisen in a nearby city. What did this place introduce, and how is it different than the normal blood sports people expect?
Ideas and questions:
It is possible that this new sport has reenergized not just the arena in which the games take place, but possibly the entire city. It could be fuller than your characters have ever seen, and might even have caught the eye of nobles, lords and ladies from afar.
You could explore from the perspective of one or more citizens who have begun to bet on the new sport. Perhaps they have a favorite champion or team, and they are willing to risk their livelihood, and you could see how both stories coincide.
Is this new sport just as brutal and hazardous as some of the other arena-based events that have been taking place throughout the realm? Or is it something that was brought about to preserve the lives of would-be heroes—something the realm might need in an unforeseen time of war?
Where does this new sport get its start? Does a high-profile noble have the money to try and experiment with something new? Or is it because of the need to be resourceful that some scrappy peasants come up with the idea?
Do the stars of the previous big-ticket events grow uneasy about the new venture? Do they try to fight back, clinging to what made them famous? Or do they pivot to a new role in the sport that has taken the realm by storm?
Writer your story from the perspective of someone who enjoys the new games, and thinks themselves capable of participating in them…with a little practice.