View Full Version : Original System Alternate D20 Skill System

2014-07-13, 06:59 PM
Im putzing around making a game that uses D20, as i really like how D20 works for most things though skills isnt one of them. My idea for skills is to convert it to a percentile system, it goes like this.
You base percentage is the skills governing stat, and when you level up you can put a "rank" in it. Each rank equals 5%, the max number of ranks you can have in a skill is equal to your level. Also im going to change the skills to be more like Fallout's skills, so there are no more craft or profession skills. Thoughts?

Edit: Also i forgot to mention that depending on the difficulty of what the player is trying the DM may add from 20% to -20% to their skill as a circumstance modifier.

2014-07-13, 07:04 PM


2014-07-13, 07:08 PM
As i feel it will encourage diversification instead of "maxing out" a few skills, also i think percentile skills are a better representation of skill than a fixed DC.

2014-07-13, 07:12 PM
No, I mean, statistically, it's the same as using a d20 and adding skill ranks and ability score bonuses. You're just multiplying everything by five.

Using percentile dice does open up a couple of options, like flip-flopping, but you don't seem to be taking advantage of that.

2014-07-13, 07:19 PM
Idk whats goin on with me today, but i forgot to mention Tag skills which increase the percentage by 10 and you get 3 at level 1. So heres an example: Lvl 1 and you have an 18 Int you have a rank in Repair and its a Tag skill so your base percentage is 33. And then you can take feats to further increase these percentages.

2014-07-15, 07:56 PM
One fault I find with percentile systems is that the chance of failure seems pretty high without fixes such as doubling/halving the difficulty or adding modifiers. However such fixes seem to undermine thinking of skill rank as a percentile (or d20) chance of success.

For instance, how does hopping across a 3' wide stream compare with leaping 20' from one rooftop to another? Does a character have the same chance? Assuming an untrained check with an average ability score (10) with +20% and -20% modifiers, wouldn't the chance of success for the 3' stream be 30% while for the 20' chasm it would be 0%?

How quickly do skills increase anyway? Can my level 1 character craft anything without a huge chance of failing?

2014-07-16, 05:15 PM
Having thought about that a bit more i realized that the base percentages are a bit low, might change it to double the skills governing stat, and go back to level +3 for ranks. That would help at low levels. Also your skills go up at level up.

Ive always felt crafting has been a bit weird in D20. Tools will help increase your odds and ill probably make a list of example items for determining difficulty, also im shortening the time it takes to craft items. 1 week to make a 1 oz phial of something is ridiculous.

2014-07-18, 12:24 PM
Apart from Tag skills, the chance of success is
2x(ability score) + 5x(ranks) + [0 or 10 from a feat] + [-20 to 20 for circumstance].
Let me restate that as
2x(ability score) + 5x(ranks) + 5x[0 or 2 from a feat] + 20 - 5x[0 to 8 for circumstance]

In D20 as written, the chance of success is
2.5x(ability score) +5x(ranks) + 5x[0 or 2 from a feat] + 80 - 5xDC

So, what you've done is slightly devalue the ability score, subtract a flat 60%, and decrease the average DC from 15 to 4, which adds a flat 55%. Alegebraicly, you've really changed almost nothing.

Tag skills give an extra 10% and 3 ranks, which is just an extra 25%. I don't see in the description which skills are tag skills; does the player choose? Mow many?

Also, how many ranks can be added each level? The way it's written it seems that everything goes up every level.

2014-07-18, 03:29 PM
A player chooses their Tag skills, and they get 3 at lvl 1 and they can take a feat to get a fourth. And as for how they increase they increase like normal d20 with you choosing which ones to increase