Radical AC idea

[ekolis]

Not sure if this was discussed previously around here, but I was discussing defenses in another context (4X games), and someone was explaining his "leaky" shielding system... and I thought it would apply perfectly to RPG's such as Angband!

Basically, there are several ways to do "armor class"...

Ye Olde 1e D&D and Angband Way: This is the way 1e D&D works, and how Angband appears to work - AC will not reduce damage whatsoever, only reduce your chance of getting hit. This seems just silly to me - if I'm wearing platemail, I should be able to resist stronger blows than if I'm butt naked!

This leads to...

The Venerable Square Enix Way of Emissivity: This is how Dragon Quest and Final Fantasy appear to work, so I'm calling it the Square Enix way. It's also used in Space Empires for the "emissive armor" component. In this method, your armor blocks X amount of damage per hit. So if you have armor that blocks 20 damage, and you get hit with anything from 1 damage to 20, you are completely unaffected! Ka-WHIFFLE! And if you take 25 damage when you have 20 armor, then you only suffer the efects of 5 damage. This system is OK in terms of realism, but it's too easily powergamed (I'm invincible, so let's farm slimes for XP!) and leads to wildly escalating AC and damage scales (You hit Golbez for 9999 damage! But he shrugs off the blow!)

Then, there's this:

The HP Multiplier System: This is used by emissive armor in the Space Empires spinoff game "Star Fury", as well as in Supreme Commander (you research advanced techs to upgrade your units' max HP). This system is better, but man, is it bland! Oh boy, now my HP bucket has 50000 effective hitpoints instead of 40000, because I got a 20% HP bonus from my armor! Whoop de doo!

And finally...

Leaky Defenses: This system is what I mentioned at the beginning. I hear it's used in one of the Fallout games, and it's also how the "ice field" shields work in this SE5 mod I was discussing! The way this works is, every defense has 2 ratings: Deflection and Absorption. Higher deflection is always better, because it's straight damage reduction. Use this sparingly in this system! The absorption, though, is more interesting. Basically what absorption says is, what percentage will the defense itself take, compared to how much it will let through to whatever it's defending? And this is expressed as a percentage: so if you had an armor with 2 deflection and 25% absorption, then if you got hit with a blow worth 10 damage, then first 2 would be deflected by the armor, leaving 8 that actually has some effect. Then of the 8, one quarter (2 HP) would be absorbed by the armor itself, while three quarters (6 HP) would be inflicted on you yourself.

Of course, adopting this in full would require a method for armors in Angband to take damage, so I don't expect to see it in vanilla anytime soon! However, here are a few thoughts as to how to implement something like this in a simplified manner:

1. Compute deflection and absorption based on a single AC value. That is, say Deflection = AC / 20, and Absorption = 100% - 99% ^ AC. So if you have an AC of 40, then you'd get 2 points of deflection and an absorption rating of roughly 33% (since 99% ^ 40 is roughly 67%). Numbers are completely arbitrary; I'm not sure how this would affect the game!

2. Treat damage that is "absorbed" by the armor as additional deflection. Or, to look at it another way, give armors infinite HP! So with the 2 deflection and 33% absorption, if you got hit with 8 damage, you'd take 8 - 2 - (33% * (8 - 2)) = 4 damage, and the other 4 would be nullified. But if you got hit with 100 damage, you'd take 100 - 2 - (33% * (100 - 2)) = roughly 65 damage, and the other 35 or so would be nullified.

The gist is, the more AC you have, the less damage you're taking for any given blow strength - but the harder the blow, the greater percentage of the damage leaks through!

Of course, this is a really wild and crazy idea for Angband, but maybe some variant maintainer would like it...

[cnp]

deflection + absorption is exactly the system used in Infantry Online. http://www.soe.com under Free to Play.
The armors are invincible (just absorb endlessly) there. They have different numbers for different damage types (so an armor could have 3 ignore (deflection) 10% protect (absorption) for kinetic damage but only 1 ignore 5% protect for explosive/sound damage.
Some armors in some zones have very high ignore while others have high protect. It is true that high ignore could facilitate farming particularly of breeding weakling monsters but this could probably be avoided somehow. Such as ensuring spawning of harder hitting monsters, or giving some weak monsters a strong attack instead of many weak attacks that they use by choice when faced with hard armors.

[ekolis]

Come to think of it... Weapons use dice to randomize damage... Why can't armor use dice to randomize protection? You'd lose the "percentage resistance" from the absorption/deflection system, but using dice would effectively abstract that idea away, and you might even be able to do away with the idea of "critical" hits as a special event - a critical hit is just defined as "attack roll was high, defense roll was low"!

Of course, it would be kind of silly to have ALL equipped armor contribute to defense against a single blow... I mean, a helmet protects only the head, and a chainmail protects only the torso, and the like! And if all equipped armor contributed to defense against a single blow, then weapons would have to be seriously buffed, or armor would need a lot of minuses to the dice rolls!

But it might be going a bit too far to go with Dwarf Fortress style body-part injuries (the slime hits your leg for 3 damage! Your leg's HP is low and you are slowed!)

So what if instead, you still had one HP pool, but each blow can only be blocked by one randomly selected piece of armor? So a 2d4 sword attack could go up against that 2d2 chainmail, OR up against those 1d3 leggings, OR up against that 1d2 helm, OR up against that 1d1 pair of boots... but not against all of them at once!

Maybe if you want to avoid unrealistic scenarios (the rat nips at your head! the giant ogre smashes his club down hard against your ankle!) you could do something with the relative sizes of the monster vs. the player... small monsters could only go against your feet/legs, and large monsters could have a higher chance of hitting your head!

Or you could roll against the total AC of all armor worn (total AC is 40? ok, then my defense roll is 1d40!) But that seems a bit unrealistic (why would monsters be MORE likely to attack the more heavily armored parts of your body?) as well as probably be a bit TOO wild and unpredictable! Unless you went with something that used square roots, so if you had 64 AC, you would roll 8d8, and if you had only 25 AC, you'd roll 5d5... but then what to do with other numbers, lol! I have 40 AC, so do I roll 6d6 + 1d4? Or 7d7 - 1d9? Or 6d7 - 1d2? Or 7d6 - 1d2? Hehe

[buzzkill]

Maybe if you want to avoid unrealistic scenarios (the rat nips at your head! the giant ogre smashes his club down hard against your ankle!)

If the ogre is smashing your ankle, it's because he has already stood you upon your head. Come to think of it, this explains the rat too.

Seriously though, if each piece of armour is to be judged individually, then you are only as strong as your weakest piece. So, in practice, you would as a character, need to steer most of the blows into your strongest armour, which is what our current system approximates already, in a vague undefined kinda way. And of course some attacks, crushing or being attacked by really huge enemies, do affect the whole body. I don't think that the Balrog is aiming for your ankle as much as he's intent on destroying everything in your general vicinity.