1KM1KT Free RPG Community

This is, of course, not about deciding which dice is better.
I have an idea for a mechanic, which includes rolling two dice, one being the attribute dice, the other the difficulty, if the attribute is smaller than the difficulty --> success. For an easy task you roll d6 for the attribute and d10 for difficulty (d6 vs d10), 2d6 vs d10 for something harder, d10 vs 2d6 for a hard task, d10 vs d6 for an extra difficult task. There are of course other stuff to it (bonuses, re-rolls, etc) that I won't go into right now, they are not even ready yet... because I have a slight feeling, that I've seen a system like this before! But can't remember the game.

Do you fellow monkeys recall a game using such a system?
Also, what are your thoughts in general? I'm not very good at maths and curves and stuff, but this mechanic might give some interesting results.

A few games come to mind - Alternity, and old FASA RPGs (Mechwarrior 1st/2nd edition and Legionnaire).

The later pair of games had target numbers based on the character's ability (ie skill level 12) and difficulty is modified by rolling more or less d10s. (As I recall, near impossible is 5d10, average is 2d10.)

has a strange system (Take a look at the where the roll is 1d20 plus or minus a second die, versus the character's ability.

I'm pretty sure I've seen other games that use dice as target numbers, or vary the number of dice rolled in opposition rather than static target numbers. Fistful of Darkness from our recent contest might have been one.

Although this system isn't unheard of, there is a reason why it is somewhat rare. Its rather unintuitive to judge the probability in such a mechanic, and blind luck has a big impact. A set target number gives much faster approximation of chance, and doesn't annoy players as much when the occasional easy task goes awry. Dd6vs d10 is a 15% chance of rolling 6, and a 50% chance of rolling less than that so... I think about 8-12% chance of failure if the math in my head is correct. (which is sorta unlikely - I'm pretty bad without a calculator.) That might be a bit high for easy, and you making two rolls, with two chances for chaos rather than a single roll.

Depending on the genre you want, this might not be bad, especially if paired with a probability mitigation mechanic. (hero points, karma pool, etc.)

I've never seen anything like it, that I recall at least, but it sounds awesome.

Cortex+ uses something like that too.

You roll your dice.
GM rolls their dice.
You can reroll to "Up the Stakes."

That's the only thing that comes to mind that something similar, but the range is larger.

Uffa - You've hit one of my pet peeves with this one.
When most people hear the word "bonus", they expect a positive modifier. Likewise, there is an expectation of a negative modifier for penalties.

Why not just have the target number increased by bonuses (and reduced by penalties)?

I'm very intrigued with this.

Also, isn't AnyDice the absolute best site on the web for game development? It's like a gold mine. I had the probability kinda worked out, but it shows so much more detail, like deviation and whatnot that works wonders when calculating modifiers.