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A staple of of early D&D is the "1 in 6" or "2 in 6" chance for surprise, finding secret doors, and so on. Recently, some of the retro-clones, mostly noticeably Lamentations of the Flame Princess Weird Fantasy Roleplaying use this as a semi-skill system. My biggest problem has been that 1 in 6 is too granular. I was considering doubling all the chances and making them on a d12 and doubling specialist skill points. I guess you could even triple them and use a d20 (with slightly lowered chances of success).

Has anyone experimented with this? Is it worth formalizing or just having them roll a d12 when I need the half-way points?

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Not sure why this was downvoted; I think it's a legitimate question, though I'm not sure about the rules change proposed. Don't downvote because you disagree with the OP; downvote if you think the question is off-topic or troll-ish. – RMorrisey Oct 4 '10 at 1:22
Can you please translate "becmi" in your choice of tags? I'm not familiar with that acronym. – Iszi Nov 4 '10 at 18:15
@Iszi: BECMI = Basic/Expert/Companion/Masters/Immortal...the Mentzer boxed sets (and more or less the Rules Cyclopedia). – HerbN Jan 6 '11 at 21:09
up vote 2 down vote accepted

When I'm running an old-school game, none of those d6 rolls are made by my players, to better preserve the players' ignorance of things that their characters don't know, such as a missed Find Secret Doors roll or even the fact that such a roll happened. In this tradition, rolling dice for these things is more like a private Oracle for what situations the DM should present to the players and their characters.

If you're of a similar bent, it would be easiest to not formalise it unless you have to. You can adjust whatever bonuses come up on-the-fly, and meanwhile you can enjoy the extra granularity without the players even knowing that a d12 is being rolled.

If you find that it works well for you and that the players have some need to know the difference between a d6 and a d12 being rolled (such as your idea for spell variants), then you could formalise it.

That said, I don't see any drawbacks from formalising it up-front, merely that you might not need to if you're already making these rolls in secret.

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Good point that the majority of these rolls are hidden. As for spells you could define the spell as giving you a roll of twice normal minus one on a D12 (for thrice minus one on a D20). – HerbN Oct 4 '10 at 17:08

As a GM, do you think in percentages?

If so, and if you're going to tweak in LFP, then skip the d12 and jump to the d20. That makes it much easier to award bonuses & penalties in 5% increments. When that 1/6 is downshifted to 3/20 the difference is miniscule (1.6%)... or what the heck, tilt it in the player's favor (4/20); it won't change the game. ;>

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I was thinking the d12 as I could just double the numbers and have the finer grain for defining unique monsters, traps, ect. But, it's true that most of the changes on 3x, round nearest, for a d20 aren't really that meaningful. – HerbN Oct 4 '10 at 17:06
The d12 would work fine, and very easy to convert from d6. It may be a question of short-term ease vs long-term options as well as use in multiple types of checks. Your call. :) – ExTSR Oct 4 '10 at 17:19

A d12 skill system can be very elegant. See for instance Lord Kilgore's direct translation of the thief skill progression to d12.

My ref uses a roll-high d12. Add your skill bonus to your roll; if the total is 12 or higher it's a success. E.g. with a +1 bonus you must roll 11 or 12, so 1/6 chance. The highest bonus for any skill is +10, since 1 is automatic failure.

In the case of Search and Listen checks though, we don't have a special d12 skill: everybody uses the same d6 mechanic. This is to encourage all characters to participate in exploration and not just "leave it to the thief".

Why d12 instead of d20? I guess dodecahedra are just cuter.

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If you’re doubling everything, then nothing changes. That is, having to roll 2 in 6 to see a secret door, and having bonus of 1 to find secret doors is a 50% chance of success; having to roll 4 in 12 with a bonus of 2 is also 50%.

When would the smoother granularity come to play?

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It would allow me to use a smoother set of bonuses for things like well hidden doors and monster surprise. I might also allow some already written in bonuses (like spells) stay at +1 or introduce weaker versions of the spells at +1 to keep one at +2 and so on. Since it would be on DM assigned modifiers I wondering if formalizing it is worth the effort or just saying "what's your number" and having players roll d12 when needed. – HerbN Oct 4 '10 at 0:52

Looking over the Specialist Rules I don't see going with a d12 and doubling the granted skill bonus would make much of a difference. The reason why is that there is only Nine abilities to spend points among. If you play into the high teens you are going to have most of them maxed out.

Unlike the +2 jump in Fighter to Hit that some D&D variants have you are getting +2 points every level in Specialist.

In the Majestic Wilderlands I went with a larger ability list and use a d20 roll high for resolution. I chose a d20 because it allowed me to factor in a bonus for ability scores as well increase in level. Now if you wanted to do this I can see allowing a d12 roll instead of a d6.

However I need to warn you to exercise caution with giving bonuses for Original D&D variants. The Monsters don't scale rapidly at higher levels like later editions. A shift of a few pluses will allow a determined and organized party to easily gain a consistent upper hand over the tougher monsters of the campaign.

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If you don't change the bonuses, it makes the base chance more important. If you do change the bonuses to match, it makes almost no difference at all, save that most people should tend to roll more randomly with d12 than with d6. (Since fewer d12's are rolled in general, it means less practice in manipulation of the dice for desired results.)

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