KingibatsSeen cited in a childrens book as an actual Dark Age game but not sure what the evidence is. Regardless, the simplicity of the game makes it a plausible Dark Age invention and it's good parrying practice for combatants.
When making centre boss shields, keep the approx. 8-inch diameter circle of wood which you cut out. Put a handle on the back that you can hold comfortably and use the bat to parry with. Make a ball by wrapping a stone in many strips of cloth or leather (a tennis ball works just as well and is safer if childen are joining in or you are playing near parked cars). Each player holds a bat apart from the one designated thrower. The thrower tries to get people out by
- Hitting any part of their body with the ball
- Catching the ball (before it bounces) when a player has hit it with a bat
If more people want to play than you have bats for, the excess just play by dodging the ball and then pick up a bat when one is dropped by a person being out. Bats can be painted in group shield colours to personalise them.