2d10 as Replacement for d20?

[darkbard]

An inquiry for those with better recall of statistics than I:

Inspired by the PbtA mechanics resolution (roll 2d6, 6 or lower = failure; 7 - 9 = success with cost or complication; 10+ = success), which relies of a bell curve distribution of outcomes rather than sheer randomness, is it possible to implement a variant system in 4E without making any other changes? Rather than the three outcomes, this would still be a success or failure (fail forward, in some cases) on the roll against the set DC or defense score: roll 2d10 + modifiers against the DC/defense instead of d20 + modifiers.

Obviously, this decreases the random component of such rolls; consequently, perhaps, it may disincentivize or reduce optimization (or, at least, math fix optimization, like expertise and improved defense feats).

Anyone have a good enough understanding of how this would affect the basic math of the game? Anyone actually try something like this?

 

[MwaO]

Basically, in 4e, you'd like the following to happen:
Things are good? 75% of the time you hit.
Things are default? 65% of the time, you hit.
Things are bad? 50% of the time you hit.
Things are really bad? 40% of the time you hit.
Things are an absolute disaster? 25% of the time you hit.

So monsters tend to go down one slot. But as long as PCs hit 65% of the time and Monsters 50%, you should be doing ok. The big problem with 2 dice is monsters can't have a 50% chance of success.

 

[Garthanos]

So monsters tend to go down one slot. But as long as PCs hit 65% of the time and Monsters 50%, you should be doing ok. The big problem with 2 dice is monsters can't have a 50% chance of success.

Hmmm I think I can set that up with a form of Roshambo++.

Let's assume this is coincidental that Arneson used rock paper scissors back in early, early design phase.

 

[Tony Vargas]

Anyone have a good enough understanding of how this would affect the basic math of the game? Anyone actually try something like this?

Champions!/Hero System used 3d6 for resolution, and was extensively analyzed, since it attracted nerds & math geeks even by the standards of RPGs.

I don't remember all the details, but as you add more dice, the average comes up more often, and the extremes less so, so if you're close to a 50/50, the first net +1 has a bigger impact than the next, and each successive bonus brings less benefit.

So it's generally good to have a very tight range in such a system, but if something does go off the res, the impact is a bit muted.

The effect would be less dramatic with 2d than with 3.

 

[MwaO]

Hmmm I think I can set that up with a form of Roshambo++.

Let's assume this is coincidental that Arneson used rock paper scissors back in early, early design phase.

I've been generally playing around with a d6 and a +/- die mechanic - PCs hit on a 3, basic bonuses to hit make it a 2+, big bonuses 2. Monster on a 4, tough monsters either 3+ or 3. Etc...

 

[Garthanos]

I've been generally playing around with a d6 and a +/- die mechanic - PCs hit on a 3, basic bonuses to hit make it a 2+, big bonuses 2. Monster on a 4, tough monsters either 3+ or 3. Etc...

I think that was stage 2 using a 6 sider, I just wonder at times if anything was really gained.

A quick example of how to on the Roshambo++, for flavor I was going with a 5 point instance and action methods like -- direct, responsive, deceptive, analytic, instinctive (wild). Hero attack wins on a tie gets a 66%... npc/monster loses on a tie unless they spend a resource with just enough resource for this to happen half the time. (or on even rounds only for DM sanity)

 

[Garthanos]

I think that was stage 2 using a 6 sider, I just wonder at times if anything was really gained.

A quick example of how to on the Roshambo++, for flavor I was going with a 5 point instance and action methods like -- direct, responsive, deceptive, analytic, instinctive (wild). Hero attack wins on a tie gets a 66%... npc/monster loses on a tie unless they spend a resource with just enough resource for this to happen half the time. (or on even rounds only for DM sanity)

If you wanted more variation in it... you can allow a character who out classes the adversary defensively to counter a win on a tie of that adversary (maybe 1 time or 2 times in a battle.) Perhaps if you totally outclass them you can turn a full loss into a win.

There is also enhancing damage of course.

And perhaps for flavor -- Enemy fighting style will define the 2 methods they primarily use.

If you want more variety of effect and make the differences in the methods feel more important have some methods win more extremely versus 1 they defeat than the other.

 

[MwaO]

I think that was stage 2 using a 6 sider, I just wonder at times if anything was really gained.

Well, there are no modifiers. Just a quick 'Do you have approximately a +2 to hit? Hit on a +. Do you have approximately a +5? Hit on a full #. Do you have approximately a -2 to hit? Go up a number and hit on a +. Do you have approximately a -5 to hit? Go up a full number.'

Thing is you can basically run defenses in 4e in about 10 seconds using this system without needing to know defenses...

 

[Garthanos]

Champions!/Hero System used 3d6 for resolution, and was extensively analyzed, since it attracted nerds & math geeks even by the standards of RPGs.

I don't remember all the details, but as you add more dice, the average comes up more often, and the extremes less so, so if you're close to a 50/50, the first net +1 has a bigger impact than the next, and each successive bonus brings less benefit.

So it's generally good to have a very tight range in such a system, but if something does go off the res, the impact is a bit muted.

The effect would be less dramatic with 2d than with 3.

Since 4e is less praying to the god of oops anyway I do not think it should be a problem to have the results cling closer to the mean.

 

[AbdulAlhazred]

Bell curves work a lot differently than a flat distribution though. If the average is 11 (2d10), then the distribution puts a lot of results near 11. 10-12 are going to be something like 40% of all the results. This means if the DC makes it necessary to get a 13, that's a LOT less likely than with 1d20. It also means that a +2 has a radically different effect in that case than in the case where you need to roll a 5 or a 17.

In the end it isn't going to cause radically different results, most of the time, but you may find that some soldier with 2 or 3 better AC than the skirmishers and brutes is not just slightly tougher! At other times the difference will be almost meaningless. It will all average out in the wash over time though.

And that's my big response really is 'Meh'. It just isn't going to change the game enough to matter. Not averaged over many encounters of various types. Nobody will really NOTICE a difference, which is the main thing.