Tournament today at Saffron Walden used the following rules and they seemed to work OK. Written so they can be upscaled for multi-player games.
When an allied army breaks, roll 1D6 for each of its units and apply the results below for the rest of the game. When all armies on one side have been broken, the game ends as normal.
If a character is with a unit at the moment of break, the result also applies to them. For the rest of the game that character cannot leave the unit unless it enters terrain prohibited to them. In that case the character routs and is removed from the table. Unattached characters automatically rout.
Units and characters that are destroyed by the enemy after and army breaks count points towards their opponent's damage score.
1. Stand your ground! The unit remains on the table. It cannot use its initiative in any way but can be ordered. Any order is at an additional minus 1.
2-5. Save yourselves! The unit routs and is removed immediately from the table.
6. We'll go down fighting The unit remains on the table and can no longer be ordered, cannot evade, and does not roll for drive backs. It must always charge on initiative (this includes Undead). It also pursues and advances whenever possible.
