I'm really starting to like the idea of mob combat the more I look at it. What I'd suggest though is totalling the STR of all the combatants before rolling any dice, to nerf gangs just a little. It would be possible to use a single value to encompass both attack and defence, unless the narrator feels up to managing both. Instead of each side making three attacks there could be three rounds of combat, with which ever side wins dealing damage.

It might also be a good idea to use simple damage states instead of ever decreasing STR values. For humans this would be infected (like malignent in the current game) and zombified. For zombies this would be disabled (for how ever many phases we determine as balanced) or dead.

Also, perhaps it would be interesting to limit inventory space to max number of items = STR value. Comments?

Working on some barricade ideas now