I am working on a new 1d100 Combat System, that is based on a percentage (100%) roll for Damage Class and Armor Class, for a game I am working on. Any feedback and corrections would be greatly appreciated.

so here's the summation of what I'm seeing here.

DC = possible damage
AC = potential damage avoided

DC * d100% - AC * d100% = damage dealt

okay, first thing, using a single die for the roll means you will have a fairly high variance, which means that results are not going to be very reliable. Since your roll results is a multiplier, it means at no point during the game will any character ever be able to perform reliably. numerically, no matter how high your stats are, you will always be subjected to the whims of the random number generator.

obviously, how this all shakes out will depend upon what other abilities you structure around it. But at this point, even a character who has through the roof AC or through the roof DC can fail in a spectacular fashion against a lesser opponent pretty much until their numbers stretch into magnitudes of difference. i.e. a person who has an AC of 3000 vs someone who has a DC of 300 can still get hit and take damage. That is all fine and dandy if that's how you want to do it. But just keep in mind that this is what you have going on here. It means that one lucky hit from the enemy can still ruin your day and pretty much drain much needed resources from a player. Some players tend not to like this, as this means things become harder to plan.

This also means that the most powerful abilities are the ones that allow you to dictate and influence the die roll. i.e. something that gives you a minimum roll of 30% if you roll lower than 30%, is EXTREMELY powerful. The next step up would be something that just gives you a designated roll. (i.e. all rolls will come out as 30%) The next up will be anything that can modify the roll in a +/- fashion. The least powerful of all of this would be modifiers to the actual DC/AC itself. However, because your formula is rather simple, you can actually calculate at what point a bonus becomes worthwhile over the other. i.e. at what point does a bonus to DC becomes better than a bonus to the roll? you can pretty much figure that out via some simple calculation.

if that's you're intent, great. If not, I'd revisit the numbers again.

of course, all of the stuff I just said is pre-mature since I don't know what the rest of your combat system looks like.

Thank you for your great input and insight. I have decided to scratch this system and go with a Fudge Compleat Combat system. It works exactly how I want it for my game mechanics.

fudge as in fudge dice? like 4d6 kind of thing? that's a radically different way of doing it. Since you're looking at a far more distributed curve, which gives you far more reliable results. That's probably easier to work with.

Yes as in the Fudge dice and Game SRD. I want to keep the game mechanics simple and Fudge allows for basic game mechanics with many ways to tweak it. I believe this system will best fit the Play-by-Post aspect on a forum. It will keep the game running smoother without the math of D&D, D20 or True20 systems.

I've actually tried that before. One of the biggest challenges you'll be meeting, believe it or not, is not the math. (Though it is significantly easier than the d20) It's making sure that people are posting and keeping the momentum going.

One of the main problems is that you'll need to continuously give feedback for every action they give you, which means that god forbid you get sick or have a weekend away, you'll end up killing your game through no fault of your own.

But anyway, good luck with the game. I think there are some online fudge dice roller pages that you can use for this too.

I have a Development Team right now and most of them are Gamemasters in Fudge. Which means there should be enough people to cover the game at all times.

One of the best Fudge Dice Rollers can be found HERE. You can modify it for any type of Fudge Dice Rolling System you want to use.