Opposed Rolls

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Before going into a post likely to be snored off, I wanted to thank Kevin Sullivan for the stats he generated on this site. The presentation of certain things are more clear there. He also provided me with a good idea on how to generate Class XP tables for Andras.

I had posted on Google Plus about a shortcut method of performing opposed rolls. The numbers do not come out the same, but I figured that they were close enough. What I discovered in studying these numbers points to effects of specific designs. In the end, I think that my design doesn't produce results that are always similar, but that produces results more in line with my design philosophy.

Specifically, the results show that:

  • Characters with equal bonuses to skill rolls under Microlite20 will have a similar, but varied chances of success under my system.
  • The Microlite20 system is affected by relative adjustments to the roll. My system is affected by the actual skill ranks and Attribute score.

Here is an example using the Microlite20 rules as written and comparing to my system.

Listen is Subterfuge + MIND.
Move Silently is Subterfuge + DEX

Aesir is attempting to sneak up on a guard. Aesir has a 16 DEX and a Subterfuge rank of 2. The Guard has a MIND of 12 and a Subterfuge rank of 4. According to the rules, the one with the highest roll wins. Each character receives a bonus to their individual rolls of Skill Rank + Attribute Bonus.

For Aesir, we get 2 (skill rank) plus 3 (Attribute Bonus in M20) to get 5.
For the guard, we get 4 (skill rank) plus 1 (Attribute Bonus in M20) to get 5.

Given these stats, Aesir will succeed 47.5% of the time. The guard will succeed 52.5% of the time because he will win all ties. By rule, ties go to the character with the highest skill rank.

Under the Microlite20 system, the chances of success will not change if the guard has a Skill Rank of 5 and a MIND of 10, a Skill Rank of 3 and a MIND of 14 or a Skill Rank of 2 and a MIND of 16. The adjustment to the roll remains +5.

In my system, success is determined by rolling-under the total of the Skill Rank and the Attribute itself. When performing an opposed roll, the Player Character has to subtract half the total of the NPC's skill rank and attribute. In this example, Aesir's Subterfuge rank plus DEX is 18. The guard's Subterfuge rank plus MIND is 16. Success is determined by Aesir rolling equal to or under 10. In other words, 18 minus 8 (half of 16). This give Aesir a 50% chance of succeeding. This is a slightly better chance of succeeding than with the Microlite20 system.

What I found surprising is that if the guard is changed as I mentioned earlier, Aesir's chances of success are affected.

sub MIND Aesir Wins
Guard 1 5 10 52.50%
Guard 2 4 12 50.00%
Guard 3 3 14 47.50%
Guard 4 2 16 45.00%

All four of these guards are identical according to the Microlite20 system, but the results are slightly different under my system. Nothing is really dramatic in the results, even with very improbable NPCs (do you hire MIND 16 guards? Would a MIND 10 guard have a 5 subterfuge skill?)

For the sake of completeness, let's say that Aesir is opposing a lower skilled guard of average intelligence. Subterfuge skill rank of 2 and a MIND of 10. Under the standard Microlite20 system, Aesir has a 62.5% chance of success. Ties no longer go to the guard, but they don't go to Aesir either because there would be a re-roll. Under my system, Aesir has a 60% chance to succeed.

Why does it give a worse chance? The amount of change is less in my system. If you compare the original example, Microlite20 provided no advantage to Aesir. He and the guard were equal. In my system Aesir had a slight advantage, thus a higher chance for success as compared to M20.

Changing to scores provided Aesir a great advantage. Instead of being even with the Guard, he now enjoys a +3 advantage. That big of an advantage yields bigger results. In my system, Aesir already had an advantage over the first guard. Changing the skill and MIND score had less effect because the amount of advantage changed comparatively less.

Somehow I'm Awake, What Does All This Mean?

Advancement in Microlite20 provides for increasing Skill Ranks and Attributes. This makes the characters very high powered around 10th level. In my variation of M20, characters cannot change Attributes except by magic or optionally by age.

I hope this means that characters can be fun to play for more than 10 levels.

This also means that using Microlite20 as a platform to develop Andras helps me get the bones of the system working well. This will be easier to playtest, especially for newer GMs. This also allows me to playtest a solo version of M2010 (my system). Maybe I have been reading too much T&T lately, but having a solo version plus the Mythic GM appeals to me.

As always, more later.

D20 + D10 Blurb

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Thanks to KJDavies for the link in his weekly roundup. Specifically, he linked to my mechanic for using roll under d20 + d10 for a skill check.

Here is a graph for your consideration:

I graphed the three mechanics mentioned in the post. Basically it shows that results above 21 begin to show diminishing returns. In other words, once a character achieves a score of 25, the benefit of pushing on to 30 is not so large an advantage.

One thing I haven't done yet is to look at this mechanic's effect on combat. Maybe it is tradition for me that I don't want to go into that direction. I'd like to say something at the beginning of Andras to the effect of this:

d4, d6, d8 and d10 are used for damage
d12 is used for initiative and surprise
d20 is used for combat
d20+d10 are used for non-weapon proficiency or special abilities. (Use a d30 if you prefer linear probabilities.)

Believe me when I tell you that if I could incorporate a d24, I would. 🙂

Next up, a crystal magic wielding rival for the Fire Primordials on their own plane and a look at the Water Primordials.

Rolling for Non-Weapon Proficiencies and Skills

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I did a lot over the Labor Day weekend. I didn't have much time to write. However, I kept battling a preoccupation with NWP and Skills in Andras. Having a roll-under d20 mechanic meant inventing an arbitrary starting point. I didn't want NWP and Skills to start with high scores because there was nowhere to go.

I had this vision of a Mage having a 17 Spellcraft at 2nd level. The problem? A 2nd level Mage being able to identify a large number of spells when he/she has two in their personal spell book. Over time, this Mage can only gain two more ranks in Spellcraft.

I could assign a lot of modifiers, but I don't want to make a modifier table for every NWP and Skill if I can help it. I could return to the slot-purchase method that is more true to 2e.

I briefly considered a roll-over mechanic and setting DC scores. But I do not want a d20 or 3e mechanic if I can help it. Nothing wrong with it, but the feel changes from something almost like 2e into something very much like 3e.

Looking at some things in my collection, I found a 2d12 roll-under mechanic. It is a great system, but alas, not OGL or Creative Commons.

Then it hit me on Sunday, but I didn't have a chance to write it down until now. I kept mulling a d20+d10 roll-under mechanic. It feels less like 2e, but doesn't feel like 3e. Will I keep it? I don't know yet.

Here's some math behind a d20+d10 mechanic:

  • There are 200 different die rolls.
  • The bell curve is actually a long plateau.
  • Using ability scores, even an 18 ability score only gives you a 62.5 percent chance of success.
Roll Roll <=
2 0.50%
3 1.50%
4 3.00%
5 5.00%
6 7.50%
7 10.50%
8 14.00%
9 18.00%
10 22.50%
11 27.50%
12 32.50%
13 37.50%
14 42.50%
15 47.50%
16 52.50%
17 57.50%
18 62.50%
19 67.50%
20 72.50%
21 77.50%
22 82.00%
23 86.00%
24 89.50%
25 92.50%
26 95.00%
27 97.00%
28 98.50%
29 99.50%
30 100.00%

In thinking about Theives' Skills, this mechanic allows me to set Climb Walls at DEX for a 1st level character. In 2e, the character starts with a 60% chance of success and can increase that ability up to 90% at first level. Starting with DEX and allowing a character to go up 6 ranks only does the same thing if the Rogue has an 18 DEX. I like that a lot. Speaking of Theives' Skills, d20+d10 also allows me to set values very close to OSRIC percentages for success for NPCs.

This mechanic also enhances my ongoing struggle with creating a skill-based Mage. The skill to cast a spell starts with INT and increases by INT Bonus at every level. So, for an INT 16 Arcanist, they begin with a Spellcasting Skill of 16 and increase by 2 at every level.

In doing the numbers, this also simplifies the modifiers based on spell level. An Arcanist casting a 1st level spell has no modifier. A 2nd level spell has a -5 modifier to Spellcasting Skill. A 3rd level spell is -10 and so on. So much simpler! In looking at creating spells using the OpenD6 system, it is also possible to create 0 level spells. They would have a +5 bonus to Spellcasting skill.

With 0 level spells, this mechanic also allows for a little bit of house magic by NPCs. Assuming an INT of 12, an NPC would have a better than 50/50 chance of casting a 0th level spell. Considering the minimal effect, this is enough to make things interesting without severe unbalancing.

The effects of 0th level spells would include things like divining one answer to a yes/no question, fists do 1d3 lethal damage for one round, divining the last image seen before death from a fresh corpse, a oen time +3 skill bonus for one usage of a Thief skill, etc. All of these effects are dependent on a lengthy casting time and verbal, somatic and material components. Without these four things, the effects are more comparable to 1st and 2nd level spells.

Lots of options are still available, but it's food for thought. You have any thoughts?