I changed the Zombie A.I. so that is a rare event. It would require all survivors on board making zero noise. Here's my revised A.I.:
ZOMBIE A.I. MOVEMENT (Determining where Zombies move)
1. All Zombies in contact will attack with both actions. If they contact a survivor with their first action, they will attack with their 2nd action.
2. Zombies not in contact will move directly towards closest survivor in line of sight (LOS), unless there is another survivor within 9 inches with more noise tokens. If so, they will move towards that survivor.
3. Zombies with no survivors in LOS within 9 inches will move towards the survivor with the most noise tokens within 9 inches.
4. If no survivors within 9 inches in LOS or with noise tokens, Zombies will move towards the closest survivor in LOS.
5. If no survivors in LOS, they will move towards the survivor with the most noise tokens.
6. If no survivors in LOS/noise tokens, Zombies remain stationary.
I think this A.I. covers all possible outcomes. I do like the no spawning suggestion if no noise, though!
Mike Demana