D&D General Brainstorming: Replacing the D20 with 2D10 - foreseeable effects?

Kariotis · Mar 30, 2023

Disclaimer: I'm biased towards D&D 4e as my system of choice, but I think this topic really concerns D&D in general and D20 systems as a whole.

I enjoy the smooth bell curve results of using double dice in many other systems. I'm sure you can't just replace the D20 in D&D with 2D10 without seriously screwing up a lot of other systems and the balance of published modules and stat blocks, but I never did the calculations or tried it out for more than a gaming session or two, where it actually worked quite nicely. I made 20 and 19 into crits and 2 and 3 into fumbles.

Anybody else tried it out? Experiences? For those more mathematically and game design-wise inclined, what would be things to keep in mind when planning to adopt this change for longer adventures or campaigns?

soviet · Mar 30, 2023

It means that results will tend towards the middle more, so the expected outcome becomes more likely. Note that combat in particular represents so many different rolls (multiple rounds of to hit and damage, saves, etc) that averaging things out even more means that the stronger side is much more likely to win. Beating a superior enemy becomes a lot more difficult.

DEFCON 1 · Mar 30, 2023

I have in fact use 2d10 for Ability Checks in a previous campaign. And I did it for the reason @soviet gave... rolls tended towards the middle. Which for Ability Checks was something I wanted-- to make having proficiency and/or expertise in a skill have more impact and meaning. With many more rolls on average falling within the 7-13 range, higher modifiers give you more consistent higher rolls. Or at least make it seem and feel to all the players that they are succeeding more often in their ability checks for skills they are proficient in.

How did it work? It worked... fine. It did what it was meant to do. Players with higher modifiers tended to succeed on checks for those skills they were proficient/expert in more often than those players who weren't. But overall... that "gain" didn't really end up mattering to the players that much. Because at our particular table and our particular style of playing... "succeeding" rather than "failing" ends up being not that particularly important to us. Failures are often just as interesting and fun to the story as success... which means it ultimately didn't matter to the players that the skills their PCs were supposedly "good at" were more successful more often than they otherwise would have been had we stuck with the d20. Failure is not a problem to overcome, it's just another interesting result. And thus for games since then, I've just gone back to using the d20 since the results of the 2d10 experiment didn't ultimately matter to the players or to me.

(In terms of why I didn't use 2d10 for combat and saves? One, the rolling of a '20' for a critical hit is much more ingrained in our psyches as players that I didn't want to lose it. And two... when it came to attack rolls almost every character had close to their maximum bonus on their attacks. Which meant everyone was rolling within like 2 point of attack roll bonus from each other. And thus the need to distinguish the "really great" characters from the "really poor" characters was not there. EVERY character was really good at their attack rolls... and thus giving the modifier bonus more "oomph"-- by using 2d10 rather than 1d20-- was just not necessary.)

le Redoutable · Mar 30, 2023

I would personally use 2d20, then either choose the lower die and gain one point of fatigue ( or whatever) , or the highest die and expand one point of fatigue ( or whatever)

soviet · Mar 30, 2023

le Redoutable said:
I would personally use 2d20, then either choose the lower die and gain one point of fatigue ( or whatever) , or the highest die and expand one point of fatigue ( or whatever)

If you can regain fatigue points that easily, wouldn't you just spend them more or less every time it helped you? This is functionally identical to always taking the highest roll.

ad_hoc · Mar 30, 2023

The game is designed so that often rolls of 8-12+ will succeed. Since high rolls are rarely needed this means that success will be the norm.

It's also not as exciting.

Clint_L · Mar 31, 2023

It turns even distribution into a bell curve, and as others have pointed out, the game tends to assume that the median represents success. Basically, you smooth out the randomness, which I don't think is as narratively interesting.

Mistwell · Mar 31, 2023

Kariotis said:
Disclaimer: I'm biased towards D&D 4e as my system of choice, but I think this topic really concerns D&D in general and D20 systems as a whole.

I enjoy the smooth bell curve results of using double dice in many other systems. I'm sure you can't just replace the D20 in D&D with 2D10 without seriously screwing up a lot of other systems and the balance of published modules and stat blocks, but I never did the calculations or tried it out for more than a gaming session or two, where it actually worked quite nicely. I made 20 and 19 into crits and 2 and 3 into fumbles.

Anybody else tried it out? Experiences? For those more mathematically and game design-wise inclined, what would be things to keep in mind when planning to adopt this change for longer adventures or campaigns?

For 5e, fumbles punish non spellcasters. Weapon users get multiple attacks, just to try and keep up with the spellcasters. If you then increase the chance something bad happens to them just for rolling more than one attack, you're making that situation even worse than it already will be. And it isn't made up for with criticals because crits just don't do that much more damage.

Clint_L · Mar 31, 2023

Mistwell said:
For 5e, fumbles punish non spellcasters. Weapon users get multiple attacks, just to try and keep up with the spellcasters. If you then increase the chance something bad happens to them just for rolling more than one attack, you're making that situation even worse than it already will be. And it isn't made up for with criticals because crits just don't do that much more damage.

Unless my math is wrong, this proposal slightly lowers the chance of a critical hit or miss, from 5% to 4%.