OD&D HD and HP Replacement Rules Inspired by Boot Hill

Inspired by Boot Hill and Violence

Series - D&D House Rules

Warning THIS IS AN UNTESTED IDEA! It might be bad. It seems fine.

Make taking a hit a bit scarier and simpler to reduce willingness to enter fair combat + speed up combat.

Inspired by the Boot Hill and the Fear of Dice blog post and also a bit by Violence. I don’t know if this is a good idea. Seems fun. Maybe I’ll try it. Someone told me this was similar to Chainmail, so I had a look and made some adjustments. Now it’s a bit closer to Chainmail.

Don’t roll HD. Every HD is now worth 1 HP.

To attack an enemy, roll 1d6. If you have +1 to-hit, roll 1d8. If you have +2 to hit, roll 1d10.

Dice Hits AC equal to
2 Unarmored -1
3 Unarmored
4 Leather
5 Chain
6 Plate
7 Plate+1
8 Plate+2
9 Plate+2
10 Plate+3

A hit removes 1 HP from the victim.

Optional rule (which will be the default if porting this system to B/X): Fighters gain an attack dice at levels 4, 7, 10, and 13.


  • OD&D: 14-in-20. This is a 35% chance.
  • my system: 5-in-6. 33% chance to hit each turn.
  • OD&D: It has 6-36hp. If it has 6 hp, it will die in about 2 hits. If it has 36hp, it will die in about 12 hits. On average, it will have 21 hp and die in 7 hits.
  • My system: it will die in 6 hits (when rolling the default d6 to attack). No variation.
  • A Giant snake that begins with full HP in OD&D will die twice as fast in my system.
  • If it starts with average HP (21HP) it will take one more hit to kill on average in OD&D than in my system.
  • If it starts with minimum HP (6hp), it will die much sooner in OD&D than in my system.

On average, the giant snake needs 1 fewer hits to die. A 1 hd enemy always requires 1 hit to die in my system. In OD&D, most 1hd enemies will die in 1 hit, but some won’t.

This removes the chance of a 1HD PC surviving an attack and getting their act together. Am I removing tension, release, and excitement? Am I removing at least some of the perceived uncertainty in an encounter with 1 HD monsters?

This only slightly accomplishing my goal of speeding up combat and making fair combat more risky. Am I close? How can we improve this? TALK TO ME.