[Red Badger]

There would have been no ‘Roughing the Passer’ rule..............

[SkyDancer]

Illegal clanging of swords?

[Tell It Right]

IIRC there were variations of Medieval Ball (sometimes called Mob Ball or Mob Football). It was not regularly played -- pretty much when the men of a village or two villages would get bored in between wars. So there were no regular rules. It pretty much involved one side trying to get the ball (sometimes made from an inflated pig's bladder, hence the name "pigskin" today) to the goal zone at the other team's village

...
by any means necssary.

People would get killed or wounded for life.

This is somewhat what early American football looked like a century and a half ago when a few young men at ivy league schools started doing it. They were recreating Medieval Ball, but somewhat toned down. Not toned down enough to keep all of them alive (the early "progressives" tried to ban football because of this, but Teddy Roosevelt himself had seen a football game and thought it had merit, so he's one of the ones who encouraged not banning it but establishing safety rules).

[NorthMountain]

Death on the football field was so common in the 1920s that the sport was nearly banned.