Players looking at the original form of Dungeons & Dragons may be surprised to discover how little Plate Armour costs. You could get the best non-magical Armour Class as a starting character.
I find this interesting. In the beginning, a level 1 character had 1d6 hit points. If a monster hit you, you would take 1d6 damage. When you reached 0 hit points, you died.
There were two primary ways of avoiding death. You could stand behind the front line so that no one could attack you in melee. Or you could have a good armour class, so monsters were unlikely to hit you.
The players in my most recent original D&D campaign quickly discovered that the best way to stay alive was to hire men-at-arms to lead the way. When I mentioned this on Twitter, a respondent said it wasn’t heroic play. I quite agree. It was, however, intelligent play.
The Nature of Luck
Hit points are a fantastic mechanic, but when they are low and death occurs at 0, a modicum of luck is required for characters to survive. Some games lean into the random nature of such mechanics, with players going through many characters until they find one that gains enough experience to become a permanent addition to the roster. Once a character makes it past the first level, the chance of dying drops significantly, assuming the character retreats when they do take damage.
More commonly, the players choose to alter the threshold of death. The standard used in AD&D days (1979-1999) was that death occurred at -10 hit points, with the character unconscious and dying from 0 to -9.
Dungeons & Dragons 3E (2000)
maintained this rule, but its implementation was flawed. The amount of damage a character could suffer in a single blow had significantly increased. Instead of most monsters dealing a single die of damage, now monsters had additional bonuses from high strength and critical hits. In a memorable session, a simple orc critically hit a fourth-level character and rolled so well on the damage (3d12+9) that it instantly slew the character.
Both 4E and 5E adopted the “if you reach negative maximum hit points, you are dead” rule as a result.
How Many Hits Kills You?
If we go back to the original Dungeons & Dragons, your number of hit dice is effectively the number of times monsters can strike you before you die. That you roll dice for hit points and damage means it isn’t entirely predictable, but a 3 Hit Dice creature typically dies on the third hit.
It didn’t take long to upend these simple mathematics. With the publication of Supplement I: Greyhawk in 1975, the year after the release of original D&D, fighters gained bonuses to their damage rolls based on their strength score, and high constitution scores could significantly affect hit points.
In some ways, this is unfortunate. It made judging the difficulty of monsters much harder. Consider a party of five 3rd-level characters against a party of five 3 HD monsters. With each hit die worth 1d6 hit points and each damage roll dealing 1d6, you’d expect it to be a “balanced” fight (by which I mean, either side could win).
When you inject one variable into this – the Armour Class of each side – you give a handicap that makes it more likely that one side would win.
Allowing “Weak” Creatures to Survive
Dungeons & Dragons 4E tried an experiment: it gave first-level characters and weak monsters more hit points. That way, you skipped over the fragility of low levels.
However, as I recall, the armour classes of some of these monsters and characters were high. Low-level combats dragged. A fight of five characters against five kobolds lasted an hour.
It is easy to make characters survive longer, but it can have unintended results.
The Rise of Complexity
These days, monsters and characters are complicated enough that it is difficult to tell the challenge level of an encounter. It is not necessarily bad because a level of complexity in combat leads to interesting play. (If your only option is “attack in melee”, then battles can get a little one-note).
In original D&D, the armour class of a character becomes less significant as a character gains levels, although it still matters. Monsters are better at hitting even high armour classes. However, because a character can survive more than one hit, you have time to react if things go badly. You still have to pay attention to numbers – if ten creatures can attack you at once and you have five hit dice, that’s not good for you.
It is also true of 5E: characters and monsters generally become more accurate. However, I have noticed that due to the slower progression of monster attack bonuses, some characters – especially with magic – can create quite incredible armour classes. However, monster damage has scaled significantly – and this may be the best method of survival.
5E has more effective healing, it’s harder for a monster to kill you in one shot, but monsters deal significantly more damage – so that two or three hits may knock a character unconscious. It is still hard to die due to the threshold of negative hit points, but in some ways, this is an inversion of original D&D.
It’s not necessarily good or bad, but it does affect how the game plays and what your expectations are.