Back to the Mud: Putting some Grit in Cortex Prime, Part II: General Difficulties

In Part I of this series, I offered some methods for modifying the core rules options in the Cortex Prime Handbook for damage and injuries to get a grittier feel. In this follow-up, I’m going to talk about some hacks for difficulty in general, because “grit” is about far more than death and dying.

As I mentioned before, Cortex Prime favors generally capable characters from the get-go and that I believe that making characters inept is the wrong way to add grit to mechanics. So we’re not going to change characters; we’re going to look at some alternative approaches to assembling pools, calculating results, and determining effects.

As a note of acknowledgment, the ideas about limiting the dice pool and the use of “Forced Dice” came from a friend of mine during a conversation we were having about adapting Cortex Prime to serve as a ruleset for my Avar Narn setting. If he gives permission, I’ll update this article to give him credit by name.

No Effect Dice, Expanded
The Cortex Prime Handbook offers a mod that removes Effect Dice from the mechanics. Unfortunately, the mod as described gives no replacement method for full degrees of effect, simply replacing all Effect Dice (where they would be used) with a d6, stepped up for a heroic success. There are plenty of games that offer varied degrees of success based on a single roll, and we could also point back to Rob Donoghue’s note about five steps stacking with the five die sizes of Cortex Prime to fill in the gap.

Rather than dividing results into “normal” successes and “heroic” successes, we can simply establish four or five sections for a granular map to convert a roll total to an Effect Die where it’s useful or necessary to do so. If you want to skip d4 Effect Dice, then you’ll have four success categories, five if you include them. I think there’s a good argument to be made for starting with d6 as the “basic” success level for mechanical ease of use, as d4’s are only supposed to be used once and then removed. On the other hand, including more d4s in dice pools increases the likelihood of Complications and Opportunities (and may further reinforce the gritty nature of a system when basic results provide only fleeting advantages).

An additional benefit for mapping mechanics to grit is that higher Effect Dice are reached less often, but this can cut both ways. It might turn many conflicts into more attrition-based slogs than the faster-moving action of the core system. A statistical analysis of the core rules for Effect Dice against the “Degree of Success” conversion described herein would need to account for many variables–average pool sizes, relative frequency of the various dice types being in pools, etc. I have neither the training nor inclination to perform such analysis for my own end systems in Cortex, much less those you might formulate for your own games. There may need to be some trial and error here.

If you’re using one of the “Damage Track” mods from Part I of this series, you can address some of this with the length of the damage track. If using weapons that add to damage inflicted, you can further tune whether weapon selection or skill rolls are most important in determining the damage of an attack. Of course, if you’re willing to make things another step of fiddly, you could have particular weapons set the thresholds between Effect Dice results (or damage inflicted) for an interesting combination of weapon and skill as factor in end result.

Personally, I’d likely skip the d4 result, starting a “basic” result at the equivalent to a d6 Effect Die, with the step of the die increased according to the following degrees: “beating” the other roll by 1 or 2 is a d6 equivalent, by 3 or 4 is a d8 equivalent, by 5 or 6 is a d10 equivalent, and by 7+ is a d12 equivalent. If you don’t mind more complexity (and more “average” results on the whole), you could increase the range of each successive step (i.e. 1 or 2 would be d6, 3-5 would be d8, 6-9 would be d10, and 10+ would be d12).

In the core rules for Conflict (or the Action-Based Resolution mod), the advantage goes to the acting character, because the reacting character must beat the acting character’s result to be successful. Many “gritty” roleplaying systems (or at least RPG systems attempting to fall into the amorphous category of “gritty”), have ties go to the defender. It’s worth considering whether to use that approach or to keep the core Cortex approach that the acting character has the advantage. I don’t think there’s a right answer here, but because this ruling applies when things are down to the wire, I expect your players will recognize the difference, even if only intuitively.

Another effect of this system is that certain “dice tricks” available with the use of Plot Points or SFX collapse into one another. For instance, the ability the add a third die to your total would now both increase your chance of success and your degree of success (whereas, under the normal rules, adding a third die to your total would make that die unavailable to be used as an Effect Die).

Limited Dice Pools
Under the core Cortex Prime rules, a character may add one die to their pool from each applicable Trait category (with some additional judgment necessary for Signature Assets and similar Traits, where having a rating within that general Trait category does not mean that it will be universally applicable). But what if they can’t? What if a character can only use a maximum of four dice in a dice pool, even if there are five Traits that might contribute a die? If this only applies to characters (players or NPCs) but not opposition rolls from other sources, this allows a great deal more fine tuning of difficulties (again, with the complexity of statistics for the Cortex Prime system, the exact steps of granularity added by such a measure is not exactly known, but we can generally surmise the difference between adding an additional d10 versus adding 2d6 to the pool–assuming we’re still only talking about using the two highest-rolling dice for the result).

To best jibe with the way the Cortex Prime system works, dice that fall outside of the character’s innate Traits should not apply to the limit–essentially, an Asset (other than a Signature Asset), an opposing character’s Complication or Condition, etc.–don’t count.

This idea also creates a new space for Traits, SFX, or Plot Point expenditures that break the rule. The ability to spend a Plot Point to add a die to the pool over the normal limit of dice should, of course, be added. Certain Trait sets, if they apply, may not count toward the dice limit for the pool–this is a great way to put added emphasis on a particular Trait set–accentuating Signature Assets, Powers, or Abilities, for instance. For a more limited version of the preceding, consider an SFX with a non-Plot-Point cost as permission to add the die to the pool regardless of the limit. I’ll be working on a post with an approach to modeling human augmentation in Cortex Prime in the near future; it will include some examples of employing these ideas for breaking the Limited Pool Rule.

This mod, I believe, also adds additional power to having higher-stepped dice in a rating. Not only does a d12 increase the total result you might reach, but it brings up the average result as well–something that you can do by adding multiple dice of a lower step when there is no limit on the pool.

“Forced Dice”
This mod works only with the Limited Pool mod above, and it’s something that I’m still wrapping my head around, so it will likely be expanded in a future post. For now, I’m just going to mention it. The idea, in general, is to create situations in which a character must accept a d4 in their (limited) dice pool. Part of determining the ultimate usefulness of this approach is finding a reason to use this method rather than the normal methods for adding disadvantages and negative conditions to the opposing pool.

Where I’m currently thinking through using this idea is where certain conditions precedent must be satisfied to undertake a particular action at full effectiveness–a character can still take the action without having first (or simultaneously) satisfied those conditions, but they must accept a “Forced Die,” a d4 added to the pool that counts toward their Pool Limit, to do so. This could be employed for taking simultaneous actions during conflict (the “multiple-action” penalty used in other games) if relevant to the way you track initiative and your action economy. It may also be used to accentuate certain conditions from the “run-of-the-mill” conditions represented by Complications.

As I mentioned at the top, I’m working on a full set of mods for Cortex Prime to run games set in Avar Narn. I’m sure there will be additional posts on this subject and others related to that ruleset on the blog soon (with the referenced post about human augmentations first among them).

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