8/28/99: I am modifying the use of the "Unstoppable Six" rule somewhat to make such events a bit rarer. In brief, if you have two characters (either PCs or NPCs) are engaged in some sort of competition and are rolling against one another (for example if one character is trying to hit another, who is trying not to be hit) and each of them rolls an "unstoppable six" the effects are canceled out, rather than as in the main rules, where both would get an added benefit of some sort. In fact I have been running things this way pretty much since the beginning, but finally decided to sit down and codify it.
5/6/00: When rolling "unstoppable sixes" in combat, each unstoppable six you roll on an attack roll, over and above any that your opponent rolls (see above) gives you an additional damage multiple. Every unstoppable six you roll on a defense roll, over and above any that your opponent rolls, reduces the attack by one damage multiple. If damage is already at the x1 multiple it is reduced to x1/2, then x1/4, etc. Successful attacks always do a minimum of one HP of damage.