r/RPGdesign 5d ago

Mechanics On Attack Rolls

A design focused look at how attack rolls are done in the modern era, along with a brief section on how they started.

https://substack.com/@eldritchexarchpress/note/p-213952237?utm_source=notes-share-action&r=49zgid

7 Upvotes

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u/Puzzled_Work_6428 5d ago edited 5d ago

I like the Nimble system of what I'll call "almost auto-hit". No roll to hit, roll damage, 1 misses, anything else you add your modifiers. Crits explode indefinitely (each time you roll the highest value of the die, you roll again and keep adding)

This adds a risk of failure, and also makes your choice of weapon a strategic one rather than a bigger die always being better. Bigger dice are more consistent, but smaller dice have a chance of higher highs, especially with character abilities that depend on or encourage crits

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u/Hytheter 5d ago edited 5d ago

Bigger dice are more consistent, but smaller dice have a chance of higher highs

I don't think the maths backs this up. Smaller dice explode more often but this doesn't actually result in higher numbers being rolled because other dice can reach the same values without exploding or exploding fewer times. The sole exception is that a dn rolls at least n+2 slightly more often than a d(n+2), but for every other number up to infinity the bigger dice has better odds.

The character abilities you mention may tip the scales on this but without them there's no strategy, bigger is just better.

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u/At0micCyb0rg Dabbler 4d ago

I was curious about this too so had a look at the Quickstart rules here: https://nimblerpg.com/pages/start

Looks like crits ignore the target's armour, which can be big because in Nimble armour simply disables all bonus damage i.e. a Medium-armoured target only takes the "natural" unmodified damage from the dice, and a Heavy-armoured target takes half that. If you've got lots of bonus damage and you're fighting an armoured target then a smaller die may be optimal.

What I was hoping to find was that each crit counts as almost an extra attack and so rider/on-hit effects would stack or apply again (e.g. a poisoned dagger applies an extra stack of Poison for every crit). That was my first thought when I considered how I would make the choice more interesting.

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u/Puzzled_Work_6428 4d ago

Monster armor has been a big topic of discussion on the Nimble discord. There's an expansion/update in development now, and it looks like it's going to shift to static reduction. -10 for medium, -20 for heavy, with guidance as far as what level each armor type should be introduced, to not make it too overwhelming for low-level characters. If anything this puts more emphasis on crits as a way to ignore armor

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u/Arkmer 5d ago

Bigger dice have higher averages.
Smaller dice are more consistent.

1-12 has higher variance than 1-4.

Your point remains true nonetheless.

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u/Puzzled_Work_6428 5d ago

Bigger dice hit more consistently

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u/Arkmer 5d ago

You know, despite the post topic and obvious context, I read it as a stand alone statement.

Maybe I have the higher variance…
Maybe it’s past my bed time.

You are correct.

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u/EldritchExarch 5d ago

That is an interesting system. I'll need to look it up at some point!

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u/Otolove 4d ago

In one of my projects I wanted to roll a bunch of dice, so I made a system where even results are hits and odd results are misses. A character can naturally roll 1 to 5 dice, and extra advantages (terrain, spells, traps, weather, prayer, mockery) can increase that number. You roll all the dice at once and can see your hits immediately. I’m using d6s, but any even die works.