Combat System Thought Experiment

So, I was playing around with dice, as I often do, and got an odd idea. It came from a fusion of several things:

1. A long time ago, we used to use extra dice as markers for characters on a battlemat, because we didn't own figures to use in play.

2. The basic combat system in OD&D relied on the idea that one man deals one man worth of damage and can take one man worth of damage, and that higher ranked men took and dealt equal numbers of men in damage and health. (Hit Dice) Their innovations which lead to D&D combat was to replace "man" with "1d6", and "rank" with "level". They complicated that system significantly after that.

3. Dungeon Robber. An awesome videogame where your characters are pathetically weak unless they get lucky. The objective isn't to make any single one of them incredibly powerful, but to retire as many as possible to fill important roles in the settlement. As you retire adventurers at various wealth levels, the town grows, and additional gear and services become available, which make survival for future characters easier.

So, what if 1 Man = 1 Die, and 1 Rank = Die Size? In other words, that die I'm using as a token to represent my guy on the mat could also be the die I roll to see his damage.

Well, first, the ranks...

1 = Knave = 1d4
2 = Adventurer = 1d6
3 = Veteran = 1d8
4 = Hero = 1d10
5 = Superhero = 1d12
6 = Immortal = 1d20

OK. So, what's the probability of a character of a given rank besting another character of a given rank? To start, let's say all combat is a contested check of die vs. die, and that the attacker lands a hit if they roll equal or higher than the defender's roll. This means the attacker always has advantage by 1.

Let's hit excel.

OK! Cool! Obviously, as each die faces off against a higher size, their odds drop, with a value somewhat above 50% when they attack another die of the same size. The d4 has the highest advantage against its own rank, with a 62.5% chance of landing a hit. The d20 has the lowest advantage against its own kind, with a 52.5% chance of hitting.

Well, that was fun! I'm going to experiment with the idea of applying size ranks to this now. A small creature is 1 die, a medium creature is 2 dice, and a large creature is 3 dice. That aught to give me all kinds of fun charts to make!

Then I'm going to experiment with using a character's die size as their hit die to determine maximum HP, with an increase in rank resulting in the addition of a roll of the new HD.

Then I'm going to experiment with different ways of determining damage. Should the recipient take whatever value managed to land a blow as damage, or should the attacker be forced to make a second roll to determine damage?

Then I'm going to experiment with weapon and armor modifiers. I think I'll make it so a character can only have a total modifier to a roll equal to their rank. So the biggest bonus a knave could get from a weapon or armor is +1; the value of their rank.

Then there's all kinds of other things to explore, like how rank progression is carried out, the application of race and class, different types of weapons, the implications for tabletop tactics...

I love this hobby.