Materials Rope!   

Setup

Spit everyone into three groups:

• Prisoners, who start with 1 dagger per 2 people (these have been smuggled in);
• Guards, who carry full gear;
• Townspeople, who start out sword and board (assuming they have a class that permits boards!).

Rope off 2 simple buildings (see image below).  One will be the prison, and the other will be the armory. Put a supply of weapons, throwies, shields, spell balls, spell strips, arrows, armor etc.

The guards' nirvana will be a short distance behind the buildings (perhaps 20 feet), and the Townspeoples' Nirvana will be a distance in front (say, 50 feet). Prisoners' Nirvana will be inside the prison.

Rules

The guards are holding people prisoners, the the townspeople are trying to free them! The guards need to guard both the armory and the prison.

The prisoners start unarmed in the prison, and can only leave when when a townsperson rescues them. One townsperson can rescue one prisoner at a time, by leading them out the door while saying "rescue... rescue..." 10 times. Once freed, a prisoner joins the townspeople team (and will be referred to as a townsperson for these rules)

All people can gather new weapons from the armory. Guards can simply walk in, pick up one item per life, and simply walk out with it. Townspeople  need to steal it, by saying "stealing... stealing..." 10 times. Townspeople my only take one item at a time, but can do so multiple times per life. Any item removed, by guards or townspeople, must be wielded by them - no removing items simple for the purpose of keeping it out of the other team's hands. On death, the player can keep the item for future lives.

A townsperson may give a weapon to a prisoner still in prison, provided it's a weapon they had at game start (and not one stolen from the armory).

Guards have the option of executing prisoners. One guard may execute one prisoner at a time, by entering the prison and saying "executing... executing..." 10 times. This removes one life from the prisoner's count. Due to bloodlust and excitement, a guard may not move or stop the execution unless attacked.

Victory This is a shatter battle!
  

Misc This will need to be tested for balance. Assuming three equal groups, the guards start with a strong advantage, in that they have a wider variety of weapons and armor. I'm not sure how balanced this will actually be.
  

Variations Make this a timed game (perhaps 15 minutes per round), and rotate teams so that each fills each position. Victory will be which town frees most prisoners, shatters the guards, or keeps the most prisoners from escaping.   

Current images: