Necropoints have been a slightly confusing issue in Dead and Back, because they're treated in two different manners.I've been wavering between how to use them for a while.
One interpretation is that NP are simply like hit points for creatures in any other game. Reanimates take hits until the number is reduced to zero, and then they are gone. The big difference from Human attribute is that there is no speed reduction for damage. Even a very though foe can be whittled down with hit and run from weak strikes. This system has the advantage of familiarity (like any other game), ease of scaling encounters (more HP is a linear increase in difficulty)
The other possibility is that NP is a threshold for damage. A creature with three NP doesn't take three hits, but rather can ignore any attack that does only one or two. Hordes explicitly work this way, but it was at times my intent to make everything like this.
Easier book keeping and greater terror are the the main draws of the second version. A GM needs only to have a list of creatures (say Betas One through Four) ignore shots that don't meet the threshold, place a check if the number is exactly right (meaning they might get up later) or cross off the name if the threshold is exceeded. Creatures as much more fearsome opponents, as every additional NP makes them exponentially harder to kill. In turn, players are more likely to need to use burst fire (thus invoking rolls to run out of precious ammo) or be forced to spend lucidity for better effect.
Unfortunately, this leads to a lot of potential problems with the players. People with low aim scores may be completely unable to do any harm to a creature with enough necropoints. Even those who do, might have trouble rolling enough successes to have any effect. Since each high roll in combat is supposed to be a telling hit, yet aside from cosmetic damage aren't really doing anything, this can be hard to describe, and be more frustrating for players than scary. It also encourages flat characters with high aim attributes and big guns to deal with threats rather than tactics or avoidance.
I would rather like to use both systems, perhaps by separating the concepts into Life Points and Necropoints. Unfortunately, I don't know if this would bring unnecessary complication to the game or lead to arguments amongst gamers about if the creature in question is an LP or NP type. Once again my lack of a stable gaming group presents an issue with finalizing elements of the game.
However, this trails on some other potential combat changes. Namely, whether there should be two aim attributes, (for close and long range combat), if stats in general should go up to seven, and a new way of reading hit dice. Since everything else is based on the top two numbers of the dice (5/6 on a d6 for normal skill checks, 7/8 means an SMG runs out of bullets after firing a burst) should damage rolls do so as well? This would unify the mechanics - but it would also increase the danger a great deal. While fast combat and character creation are ideal, high attrition rates are somewhat less so. This also seems a bit odd from a genre perspective, as the rate of getting a head shot or otherwise disabling a creature with an adequate weapon is now 25% of the time. (1 in 8 chance is kind of high too, but a bit more acceptable)
Since it may have confuse some, there two good reasons why aim is separate from the other attributes. First, its more of a gestalt of everything - coolness under fire, eyesight, raw strength etcetera - than identifiably derived from one area. Its a well know phenomenon for a small and fast, yet not particularly strong person to be a better martial artist than bigger people, and depending on which style is used, other factors come into play as well. The second reason is simple matters of game design - no dump stats.
Other notes about combat should appear in a supplement that should be released by the end of the month.