the combat of Dark Souls

Something a friend told me years ago was that he hated Armor Class because it doesn't make sense in a realistic manner. Thick heavy armor wouldn't make you more difficult to hit, in fact the opposite, and it would be worn to lessen the damage when you do get hit. Something that Dark Souls doesn't always do very well, but it does follow the idea that heavy armor slows you down. Armor is only a marginally good thing to have, especially if your character is kitted out for speed. This is why you see so many people play Dark Souls wearing little to no armor whatsoever. A lot of armors give different benefits however. Some provide bonuses against magic damage or poisons, while doing next to nothing for physical damage. By comparison, armor in Dungeon & Dragons just gives a static bonus to your Armor Class.

Combat in Dark Souls is pretty straightforward, but still has a lot of depth. When confronted with an enemy's attack you can choose to block, dodge, or parry. Blocking is pretty easy, and is the default method of handling most attacks. You get hit and your shield or weapon takes some of the damage off. Dodging requires a little player skill because you have to dodge away from the attack, and that's not always in the direction you might expect it to be. A successful dodge avoids all damage, but failure means you get hit and more often than not your armor only takes off a little amount of damage. Parrying negates the attack completely, but can only be performed on certain attacks and is difficult to pull off until you "git gud."

To Parry a Boss

If basic combat in D&D is a question of blocking, dodging, or parrying then I think traditional Armor Class would have to go away. Armor would continue to be rated as light, medium, or heavy in order to see if/how movement is affected but would do nothing to evade being hit. In fact, the heaviest armors would make it quite easy to be hit. But armor would negate some amount of damage based on its weight.

Here's my game theory ramblings now.

By reducing the die type of damage dice you effectively hobble the damage coming in and still keep it relatively random. Light armor would reduce damage by one point, medium armor would reduce the damage dice by one size dice (i.e. a d8 becomes a d6), and heavy armor would reduce the size of damage dice twice. An attack inflicting 1d10 damage normally would do 1d10-1 against an opponent wearing light armor, 1d8 against medium armor, and 1d6 against heavy armor. If an attack does multiple dice of damage then it could lose dice once being reduce to d4s but no damage could be reduced below 1d4. Shields would act like medium armor, but actively blocking with one would require a save or else you can't do anything else this round like attacking or drinking a potion or casting a spell. In other words, the force of the attack staggered you momentarily and you have to wait until next round to recover.

Dodging would be a Dexterity-based roll against the opponent's attack roll, and maybe the size of the weapon would act as a modifier. Small weapons are easy to dodge, large weapons are harder to dodge. A successful dodge would negate damage and set you up to act first in the next round.

I don't think I've ever seen good rules for parrying, and in Dark Souls a successful parry riposte can be a devastating attack. Parrying would have to be an attack roll against the opponent's attack roll, and of course could only be performed against a traditional weapon like a sword, ineffective against claws or bites or anything weird or unusual. A successful parry would give you an opportunity to attack and your opponent gets no ability to react, which means some opponents could do it to you too.

I'll have to think some more about this.