I really, really dislike hit points.
Here’s an example. According to the official rules (paraphrased), at or above half is “no signs of injury”, half to 0 is “a few cuts and bruises”, and a hit that takes you to 0 or below is a serious injury.
Even as an abstraction, it’s sort of broken, and especially when combined with Armor Class. We’d probably call it a leaky abstraction in software, although it’s slightly different.
The intent is to model abstract survivability in combat. Your stereotypical orc and human fighter, armed with medium hand weapons (swords, axes, etc) and a shield, wearing decent armor, set to murdering each other. Since each is pretty equally matched, the fight goes on for a bit. They swing and score the occasional hit, but not one that is especially damaging. Eventually, one of them will have their “luck run out”: perhaps literal bad luck, or the exhaustion of hand-to-hand combat combined with numerous small wounds, but in any case, one of the combatants will score a serious hit and put the other out of the fight – if not 6 feet under.
This is perfectly good abstraction for our 2 perfectly average combatants. There’s problems, though:
- Critical hits are boring. A critical hit with a dagger does max damage: all of 4 points. You have a 1 in 4 chance of having that happen anyway. A critical hit should actually do some damage. Having a game where certain weapons are simply useless is bad.
- Armor “makes you harder to hit”, which is another annoying abstraction. It’s assumed that you’re actually being hit, but the blow is “turned”. But now, when a hit is scored, the armor – no matter how good – does nothing. So armor is a binary prospect: it either protects you utterly or fails completely. In our perfectly average example, the abstraction is fine, but in larger combats (as one example) suddenly my plate mail is less strong.
- Healing is perfect. Get to -1 HP, but luckily survive the fight? No problem, you’re fine! I understand that D&D is not intended to replicate the very real effects of actual wounds, but it’s a little annoying that you’re just a lump of magic putty that mends perfectly by resting.
I don’t know that there’s an easy, backwards-compatible way to fix this. In my head, I’d do something like allow the advantage dice to determine the effects of a critical; so if you have a 20 and an advantage dice score that would also be a hit, then the target loses half their HP total (or is at 0 if already at or under half); otherwise it’s double damage, or something.
You get into problems with a dragon being able to kill a dragon, but hey, why not? The dragon exists, the fact that the players are fighting it int he first place requires a bit of suspension of disbelief; why can’t a lucky halfling stab in just the right place? Why can’t a stout dwarf swing his mighty axe with such ferocity that the fearsome wyrm is struck down? Is it better to play a long-game of numbers and averages?