I can also test "Ghost Dance" which is immunity to bullets--I just run a simulation and then manually set each battle against a gun-user to 100% victory. The bullets just "pass through you."
However, there are some problems with this--and Ghost Dance points these out.
1. In the same game where someone is likely to shoot you the are unlikely to also stab you (at least not with a sword)
Oh, sure--you might face a knife--but if a character is immune to bullets in a modern day (one where guns exist) the other 1/2 of the attack types are very uncommon (sword and blaster are uncommon). Now, granted, that changes if people know you are weirdly immune to bullets--but again, that's a weird game.
2. If you are immune to bullets you are usually a very good combatant in some other respect
Most of the characters I can think of who are immune to bullets would be warriors of some type--and usually not using guns (martial arts? swords? super powers?).
This further exacerbates the problem: if you take away guns from most modern attackers and you are a kung-fu master you further open the gap.
What Do We Learn From This?
The key learning (which we already knew) is that although the simulator treats Blaster, Punch, Sword, and Gun as equals (and Armor, DP, and Force-Field too to some degree) they, in any real game, are not. Since the attacks and defenses are theoretically balanced and relatively interchangeable that is okay until you do something like isolate Gun and then treat it like the artificial environment of the simulator is actually correct to real games.
But we can do things. What things?
- Arbitrarily increase the cost. Let's say that immunity to gun wound up costing 1/4th your points in the simulator. We could increase that to 1/3rd and decide that in a real game that's how much it's worth. This is, as I said, arbitrary--we do some mental calculations and decide that for-real immunity to bullets is likely to appear in Chi Martial Arts and (some) modern-day magic games and it means you are largely immune to "the police" (the guys in those games who'll use guns) and we think that's worth (on a social level) a little more. Or, maybe it's not (who cares if your modern day magician is immune to bullets--they're supposed to be freakin' magic).
- Actually decrease the cost. Maybe the real question is: is any PC in these games (or named NPC--an important points-balanced character) buying Gun? If not then maybe it's worth less. As noted above, if no points-built character would spend points on Gun then what are you "balancing" the PCs against? There's an argument that this should be free--but even entertaining this approach I wouldn't go that far.
- Increase the "incidence" of Gun from 1/4th of the attacks to 1/2--use Blaster as well. A fairly canny approach might be to say that in most gun-using games guns 'fill the role' of Blasters so Guns represent 50% of the attacks and Blaster 0%. This is, to my mind, pretty good thinking but in light of the above argument it might not be the most play-balanced approach.
- Do nothing but make sure the GM limits the purchase of it. The GM (and the other Players) have ultimate say over what's available for any game (in a modern-day detectives game players are prohibited from buying mutant powers and cybernetics). This might go further: there could be some Chi martial arts games (lower powered ones) where you want the PCs to be vulnerable to bullets so they can't just invade and take over a police station (that might be hard anyway with all the nightsticks and non-gun weapons--but the point remains). On the other hand, if the PCs are 150 CP, 40 AP, Scale 4 Chi Martial Artists, giving them access to standard cost Immunity to Guns isn't going to change how they could rampage in a police station--it just now means they could likely take on an army base. That might be fine so long as the GM and other players are aware and okay with it.
- Price it differently for different games. This is a can of worms to be sure but we could do it and it would make some sense. There are already some clear precedents for this being a good idea (being a huge naturally strong in a Warhammer 40k Space Marines game isn't worth nearly as much as it is in a fantasy game) but we've really tried to avoid that (and, to be fair: if you are allowed to be "as strong" meaning 'as many points spent' as 'were spent' on your heavy melter then you will be just as effective punching as using the heavy weapon).
What do I favor?
Good question. Right now it's the forth. However the third seems (as I said) like some good thinking. The important thing to keep in mind, of course, is that just because the simulator prices something some way doesn't mean that's the way it is.