d100 Checks against 3d6 Stats

1
I like d100 rolls, even though I mostly ever play with d20 systems. You encounter percentages every day in your life and thus can gauge your chances at a glance, while a d20 roll can be trickier. I mean, what's easier to immediately grasp - a plain d20 against DC 16, or a percentage roll against 25% odds?

Then you add bonuses to the mix

• Roll against DC 17 with +3 bonus.
• Roll against base 65% skill with -30% difficulty adjustment.

and d100 is much easier to understand.

2
I like 3d6 stats, probably because I mostly ever play with d20 systems. They are so deeply ingrained in my mind that when I see something like Strength 58%, I just don't know what to do with that. It doesn't look right, I want my attributes in the 3-18 range. And yes, that is nothing but personal preference, but so is any other discussion of a gaming system.

3
I like attribute checks. Skill systems and all are great, but what if you suddenly get a corner case that doesn't fit under any of your carefully defined skills and you don't want to pluck a DC out of the thin air? Plus you can use them in place of specialized Saves, where they make a lot of sense - rather than some nebulously defined Save vs Magical Devices, roll against Dexterity to dodge the ray, or against Endurance to tank it.
 

 
And here's the conundrum - how to make my flights of fancy fit together into a coherent system? They are pretty disparate bunch, after all. Yet I might have a possible solution (aside from telling myself to go and do something more productive).

Use your normal 3d6 attributes, but when you wish to attempt a stat check, multiply the attribute score by a number corresponding to the difficulty of the task from the table below. This gives you a percentage chance of your success, and also gets rid of any further adjustments, as they should already be taken into consideration when deciding the difficulty.

We are still somewhat "plucking a DC out of the thin air", but I believe it's easier to say that a task is challenging than coming up with a DC 14 to beat. So guesstimate the difficulty, multiply the attribute and you have a percentage chance of your success:
 

Difficulty	Multiplier	With 8 in Stat	With Average Stat	With 16 in Stat
Easy	x7	56%	73.5%	112%
Normal	x5	40%	52.5%	80%
Challenging	x4	32%	42%	64%
Hard	x3	24%	31.5%	48%
Heroic	x1	8%	10.5%	16%

 
Easy: An average person can do this reliably and somebody skilled shouldn't even need to roll in the first place.

Normal: A toss-up for normal people.

Challenging: This is where the inadequate will start to really struggle.

Hard: A toss-up for talented people.

Heroic: This is a d100 roll under the basic attribute score. At the very, very best, you will have a 1-in-5 chance, and that's only with game-breaking stats. An average person can cross their fingers and pray, yet even those truly gifted will most likely fail.

Your average 3d6 attribute will have a score of 10.5, so a normal task will have a 52.5% chance of success. I can live with that little extra bonus over equal odds.
  

by Mateusz Mańka

Q: Hey, you claimed this will be easy and intuitive, then suddenly you want us to solve math?!

A: Well yes, but it's simple math!

Q: Aren't the chances a little low? For an average character, a normal task is 50/50 and an easy task has just under 75% chance of success?

A: Let's take for example Lamentations of the Flame Princess for comparison, shall we? A 1st level Fighter will have +1 to hit, and attacking an unarmoured opponent (AC 12) should be a normal task for them. They will have exactly 50% chance of a successful hit, so I'd say my percentages are not that far off.

Funny how the chances don't look so good, yet nobody bats an eye to roll a d20 against such odds.