I was thinking about Quiddage and Harry Potter and basically the rules... and when I did... I'd make two changes...
One is a very boring "Changing how the league format is done to be less reliant on total points"
The second is controversial but frankly it is the worst part about the sport...
I'd remove the Seeker and the Snitch.
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Think about it this way... Imagine Soccer where during the game... There was also a Track and Field race to the side... and that the result of this race was like 90% of the points.
Yeah theoretically you can earn more points playing the game then the Snitch will give... But not only are those rare BUT are typically situations where either the Snitch doesn't show almost at all (games in theory can last more then a day... and not "Come back later" either...)... OR where one of the Seekers was taken out and the team is intentionally delaying the game...
In other words it is also an anti-fun mechanic for people playing. SURE really fun for the fans...
Note: This isn't a criticism of how the game works in the movies/books... MANY sports in history were broken and serious problems even after they were made professional. Many of its biggest issues are things that existed in real life even today! (Games without a reasonable end point, Far too dangerous, Rulebook is secret, stupid nonsense rule, League system broken, Overfocus on sports over everything else... seriously why are like 80% of the house points the stupid sports games?, Flagrant cheating)