Set up a bridge that must be at least 8m long and wide enough to accommodate four fighters in the front row.
At each end of the bridge is a shield.
Each team is made up of an equal number of fighters, with a minimum of 4 in each group.
You need to set a respawn condition (limited time, run to a given point and come back, etc).
How it works :
To win the game, you must either kill all the fighters on the opposing team, or hit the opposing shield with a hand-held weapon.
When a combatant is killed, he/she exits the bridge from the side to cause as little disruption to the fighting as possible and must fulfil the respawn condition that has been chosen.
He must then return to combat via his team's starting point.
Remarks :
You can add an extra rule about the number of respawns possible. For example, each fighter has only three lives. At the end of the third, no more respawns are possible until the next game.