Skills revisited: Dice pools and the LotFP playtest rules

So obviously the first thing I should do once I say that I want to play some more 5E is to start analyzing the rules for Lamentations of the Flame Princess.



Just a few days ago, I grabbed a copy of LotFP's Free RPG Day supplement for the year, Eldritch Cock.  It has a whole bunch of spells in it, but also what I think is the first unrestricted release of the LotFP playtest rules, a set of backwards-compatible rules changes for the game.

One of the coolest things, in my opinion, is the update of Saving Throws. They are now based on a d6 dice pool. Number of successes determines the result (2+ = full save, 1 = partial save, 0=fail). The only variable is, are you saving against a magical effect or not? I am a bit biased since I love dice pools inherently, but I think that this is a great improvement, at least on paper. Saving throws have always been a high hurdle to clear for lower-level characters. I want to see exactly how this plays out at the table.

Meanwhile, of all the great things in LotFP, the skill checks were the one thing that I never really liked. you have an n-in-6 chance, a single d6 roll. So (a) you want to roll low, and (b) you could end up with a 6-in-6 chance to do something if you buy enough of a single skill as a Specialist.

I mused on a potential upgrade to that here.



The playtest document (at least the one I scanned a while back; I don't know if James updated the rules in Eldritch Cock since I don't have it on me right now), essentially boils down to the following paraphrased rules:

- One random skill starts with a +3 bonus, and another begins with +2. If this is the same skill, it adds together to only be +4. (Target number for everything is 6 on a roll of d6, by the way. So in this case, failure only occurs on a 1.)

- For each bonus skill point (affected by INT), determine the skill randomly. negative modifiers start wiping out the starting bonuses from the last step.

- Specialists get 4 +1 bonuses to distribute at will at level 1, and add +2 per level.

- Roll 2d6 with 2x6's/2x1's being successes/failures if your total bonuses for a particular skill are less than 0/greater than +5. (Don't worry if I wrote it out confusingly because I kind of ignore this moving forward in my thought experiment.)

I wanted to see if I could keep the dice pool idea going from my original idea, and then see if I can adapt the playtest rule to follow the same model. We're already set to use a dice pool for saves, so why not skills?

(Forgive me because I'm now kind of writing this as I go...)

So first off, realize that the default skills follow a linear progression. 1 skill point is the same value (a 1-in-6 increase in probability) for all time. Your chance of success is 16.7%, 33.3%, 50%, etc. So in these playtest rules, every character has a 66.7% of success at a single skill, and a 50% chance on a second skill. Or they get the same result twice and get a single skill at 83.3%. Everything else stays at 16.7%.

So imagine we're using dice pools instead. The default of +0 Dice to a skill still gives you a base success chance of 16.7%, so that's good. In order to get closest to a 66.7% and a 50% chance for two separate skills, we'd need to add +5 dice and +3 dice, respectively, to each skill to yield success chances of 66.5% and 51.8%, the probabilities of success of dice pool sizes of 6 and 4. Let's accept that as our baseline, pre-tweaking value of dice for everyone.

Then comes Specialists. They get four +1 bonuses that they can arrange to taste. It's not easy to convert this to a dice pool, since they could add all +4 to a single skill, making a 1-in-6 chance a 5-in-6 chance. In dice pool terms, that's adding 9 dice to get your chances of success up to 83.8%...

(Before we move on, here's the incremental success percentage increase with each new die added to your pool: 2nd die = +13.9%; 3rd = +11.6%; 4th = +9.6%; 5th = +8.0%; 6th = +6.7%; 7th = +5.6%; 8th = +4.7%; 9th = +3.9%; 10th = +3.2%. If we average all these, we get about 7.5% per die.)

So back to Specialists. It looks like, to keep the +4 starting bonus consistent, we should convert it to +8 or +9 dice in my suggested dice pool system. They would clearly have the most benefit if you spread them all out over eight or nine different skills, with each one getting, therefore, a 31% chance of success. In this extreme, they're almost twice as effective as the +4 dice of the playtest rules. The playtest dice are more effective per skill (33.3%>31%), but you can only apply that bonus to four skills at most.

I... actually kind of like that approach. I think that the jack-of-all-trades seems more consistent with my idea of what a Specialist class brings to the table, which is the guy you hire to do the tricky stuff. I'm going to assume players will game the system, most likely spreading their bonus dice far and wide. However, if they want to tailor their character to fit a particular archetype, they can shift that pool around quite a bit. (Translator, Sailor, Acrobat, etc. are all merely different skill distributions.)

One last thing that I really like: in keeping the mechanics of skill rolls consistent with that of saving throws, not only are we unifying mechanics a bit, but we can also introduce variable results for skill rolls. 2+ successes means the skill is executed perfectly, whereas one success means there is a complication that develops. The downside to this, of course, is that most skills used by non-specialists are going to forever remain at 1 die, leading to automatic complications. I don't know how I feel about that yet.

What remains to be seen after this first thought experiment: (1) Do I want to tweak the amount of bonus dice for non-Specialist classes? It depends on whether the Specialist seems too crucial compared to the Fighter and Magic-User. (2) What about that INT bonus? Keep it consistent? Again, more playtesting required. (3) Maybe I'll give fighters bonus dice for Leadership, another new skill.

Game Mechanics: Dice, Doors, and Decimal Points

So I have a skill system hack I am working on and I want to share it with you.

Start with Lamentations of the Flame Princess, the rules set I am using for my Megadungeon Madness game. It's basically B/X but with some tweaks (ascending values of armor class, a silver piece standard, and no codified bestiary, for starters).  One of the nice things about it is that skills are based on d6 rolls. Virtually everything is a 1-in-6 chance, and specialists (read: thieves, but a less pigeonholed concept) get to invest points into expanding these skills. E.g., put two points in Sleight of Hand and your chance to execute such a task goes from 1-in-6 to 3-in-6.

I am hacking that d6 system a bit. Mostly because I love dice pools, but there is also a logic behind it.

First off, rather than expanding the range of success, I expand the number of dice you roll, while keeping 6 the target number. Note that statistically this is more difficult. For example, it is harder to roll three dice and get a 6 than to get a 4, 5, or 6 on a single die (the 3-in-6 case):

(A) Dice pool: 3-dice probablility = 1-(5/6)^3 = 42.13%
(B) One-die probability = (3/6) = 50%

A solution to the increased difficulty is that the GM should be more generous with the bonus dice. We already add dice based on invested Specialist skill points, but let's also add Ability Score bonuses. A +1 to Strength is easily added to your pool if you want to Open Doors, for example. Have a crowbar? Add another die. And so on. This borrows heavily (if it isn't identical) from the "negotiated skill system" that I heard used on the Dwimmermars game of +Adam Muszkiewicz (of such notable endeavors as Drink Spin Run, Metal Gods of Ur-Hadad, and whose name I can apparently spell without having to Google it now).

Another nice feature is that the bonuses can easily go to six or higher. Whereas a 6-in-6 chance of the basic one-die system is a guaranteed success, a pool of 6 dice is only going to yield a 6 at a rate of 66.51%. So don't be afraid to be liberal with your bonuses.

The problem that we have already come across thus far in my Megadungon game is that opening doors is still fairly likely to result in failure. Even with crowbars, people helping, and strength bonuses, you are pretty likely to not open the door.

This is where I got the idea to go straight into story game territory and offer the players a narrative choice. In the first option, the players could choose to let the door be. The door is swollen shut, just like St. Gary said it probably would be. The other option is to note your margin of failure. (E.g., was your highest result a 4? Then your margin of failure is 6-4 = 2.)  I'll let your character(s) persist at opening the door until they succeed, but I get to roll the margin of failure in Wandering Monster checks. (A dice pool of 2 in this example.) Again, each of these is a simple 1-in-6 chance.  The logical basis is that the worse your initial check result, the more noisy your success is going to be and the more likely you are to attract attention to yourself.

I think this is a pretty elegant mechanic for doors if you're going to go Full Dungeon Crawl. I'd like to think that my game ups the tension by emphasizing slow, careful mapping, and keeping track of resources, etc. Wandering monsters (or more accurately, random encounters) are another high-stakes element, and it's nice to put the devil's bargain in the players' court.  The alternative would be to have the players reroll the check while I check for the random encounter with each failure. This has the potential to be tediously drawn out, especially if the player has a small dice pool.

I've already used this mechanical tweak in one full game session, and the resulting random encounter was deadly. But more importantly, the decision of whether to push forward at the door had a lot of gravitas behind it. In all, it's an idea I'm quite proud of, given that I'm only starting to break out of the habit of sticking to rules as written. I'd probably have broken out of that habit ages ago, but it really requires sitting down to run some real games.