Novel from 70s or 80s. Pretty sure it was a Hardback (checked out from library) in English.
The setting was very similar to the Rollerball (1975) movie. The broadcast of the show is the "Bread and Circuses" used to control the masses.
I get vibes that the title was something like KillBall or KillBowl. But have not located anything in Google searches.
The book focuses on the aging Quarterback of one team.
The games were played in run down sections of the city. covering several city blocks. (maybe like 10x6 city blocks). It was not an open field. The players would dodge around building/houses and many times even through them. Busting through doors or flimsy walls or fences. (I recall one scene a player, the Aging Quarterback I think, taking a break in a public restroom to get warm. It was the middle of winter in the city.)
The players had a pouch on the front of their jersey where they would carry the ball, so they would have their hands free. Pretty sure it was legal to fight if you got cornered with the ball.
IF I recall correctly one of the players (The Safety?) was equipped with a rifle/shotgun with one round (per game? Per quarter?) that he was allowed to shoot the opposing teams ball carrier with to stop him.
They did not wear normal Football padding, it was more like Combat Armor/Helmet. So I think the Safeties typically would do Leg shots, as shots to the head or chest/back might knock the ball carrier down, but they would be able to get back up and keep running.
I think the Aging Quarterback, starts noticing that the opposing players on many of the last few games seems to be getting help in winning. (inside info? or advance info?) so that they can avoid ambushes to stop them from scoring goals.