The Aurora RPG Engine – Part 9

Creating the Base Pool

After going through nearly the entirety of the resolution system and outlining the bits that happen once the base pool has been gathered, it’s well past time to cover how that base pool, and its baseline value of 5 dice, is generated.  This is no trivial matter.  As every test or roll made by a character begins with these values, what gets included, measured, and listed on the character sheet not only defines that character but also has a huge influence on the overall genre, tone, and playstyle of the entire game/campaign.  These values say what’s important about the characters, and thus what’s important about the game.  They influence how the players view the characters, how they approach things, and what kinds of actions they will take.  They provide flavour and guidance and ultimately are the lens through which the players/characters know themselves.  All in all, the way characters are measured and defined is one of the most important choices in designing the campaign. Continue reading

The Aurora RPG Engine – Part 8

The Twist: “Buying” Success

Riffing on the previous concept is a twist that complements the idea of MoS from the opposite direction:  If I fail the roll, or if I succeeded but want extra MoS, I can “buy” extra dice to succeed (or succeed better) at cost.

While this doesn’t preclude the recommendation of using a “fail-forward” concept in scenario design, there are still times where I might want my character to succeed in this moment, right now.  And so I have a choice… let things continue as I rolled them, or am I willing to put my character into some narrative (backed by mechanics) peril in order to get the win?

If I choose the latter, <devilish voice>excellent</devil>.  Much like the ladder of options for MoS, each extra die bought in this manner raises the magnitude of the potential trouble.  The number of dice to be bought doesn’t need to be stated up front, allowing them to be bought one at a time, rolling and adding to my total and gradually raising the stakes until either my character succeeds or I reach my limit of peril.

Note that the narrative/perilous cost of the extra dice is paid whether they lead to success or not! Continue reading

The Aurora RPG Engine – Part 7

The “Extra Die” Beauty: Creating a Margin of Success

Now we get to the key idea that really makes Aurora sing:  After tallying enough dice to reach the target number of 15, any “remaining” dice count (as in counting the number of dice themselves, not the numbers on the dice) as the Margin of Success (hereafter often noted as MoS).

With this innovation*, a Margin of Success mechanic is elegantly added to a dice pool system that keeps things moving quickly and, most importantly, preserves the pool’s visceral nature.  By dealing in dice (and by having/keeping a fixed target number), there’s no need to calculate something fiddly such as “for every 5 points over the target number you have achieved an extra level of success.”  Count out to 15, move the rest of the dice to the side, and there’s the Margin of Success.

With this, the many great options and advantages of a Margin of Success system open up:

  • Provides for more interesting narrative outcomes. With an explicit MoS system, the players and GM know not only if the character succeeds or fails, but also how well or by how much.  Did they just narrowly make it?  Succeed with style?  Fail miserably?  Or did they shine in a moment of glory?  This gives everyone a tool to create and craft a rich and more exciting scene and story.
  • AND, using the “Buying Success” mechanic detailed in the next section, it allows for tension, excitement, and a great story even if the character fails or just ekes out a win.
  • Allows for the easy creation of cumulative or extended tasks, compiling a count of MoS towards completing a goal.
  • Explicitly allows the coupling of success in combat (or other conflicts) with the skill roll, avoiding the oddities (and often frustration) of excellent to-hit rolls yet terrible damage rolls, or vice versa. This makes the skill roll more important and thus makes character ability and agency more relevant.
  • By leveraging MoS as a type of “currency,” interesting subsystems can be added, such as spending MoS to activate special abilities, create advantages, or other creative and exciting outcomes.

Continue reading

The Aurora RPG Engine – Part 5

Baseline Values and an Aside on Probabilities

The base number of dice for a skilled entry-level professional is baselined at 5 dice.  With 5d and a target number of 15, the chance of success is roughly 75% (in actuality it is a bit over, but close enough).  As outlined in this previous blog post, this falls into the probability range that I find is most perfect, where a competent, trained, healthy individual beginning their professional career should succeed on almost-routine tasks (I say almost, as if it were perfectly routine there’d be no need to roll a test!) most times.  And even in those instances where they fail their roll, rarely will it be too disastrous of a setback (especially if the player chooses to succeed at cost, which is further explained below).

By adjusting the dice pool up and down in increments of ½ dice (a d3) allows for roughly this progression of success chances:

3d 10%
3½d 25%
4d 50% (actual is 45%)
4½d 66%
5d 75%
5½d 90%
6d 95%

In graph form, it looks like this (courtesy of

In play, it is easy to remember that 3½d to 5d forms the middle ground of success probabilities.  Anything less than 3½d is super unlikely to succeed, and anything over 5d is pretty much guaranteed to succeed.

Taken together, everything comes together nicely:

  • A nice round target number that is easy to remember.
  • An easily graspable number of dice that counts as “competent”.
  • Enough dice to let beginning characters succeed despite modifiers while also tempting the players with extra actions.
  • And an intuitively graspable notion of the chances of success.

Continue reading

The Aurora RPG Engine – Part 4

Fixed Target Number and Difficulty as Dice Modifiers

There is one main disadvantage to most dice pool systems:  the time it takes to total the rolled dice.  This begins to get especially tedious around 7-8 dice and only increases thereafter, slowing the game and potentially killing its momentum.

A second disadvantage also arises if the system uses a series of increasing target numbers (for example, setting a target number of 10 for an Easy task, 15 for a Moderate task, 20 for Difficult task, etc).  Doing so undermines the intuitive feel of “Number of Dice = Chance of Success”.  If I have 8 dice in my hand versus 5 dice, I should feel as though my character is more capable; however, if the target number is also changing/increasing, then it’s tough to gauge whether those extra dice really are leading to an extra chance of success.  With two variables at play it creates a matrix of possibilities that hinders any automatic and visceral feel.

By setting the target number at a fixed value of 15 and by adjusting both for the difficulty as well as accounting for all other modifiers by adjusting the number of dice rolled:

  • The number of dice rolled at one time is generally kept low.
  • Even when many dice are rolled, we only need to count enough dice to make 15, which can be easily done by adding together the highest dice until 15 is reached. (The remaining dice are used as a “Margin of Success”, to further explained below.)  This avoids needing to tally large numbers of dice.
  • And because the target number never changes, we easily grasp the chance of success by the number of dice in our hand. The visceral nature of the die pool is maintained.

Continue reading

The Aurora RPG Engine – Part 3

Base Underpinnings and the Dice Pool

At its fundamental level, this is a d6 dice pool system, chosen for the numerous of advantages it brings to the table:

First and foremost is the pure visceral aspect of a dice pool.  By holding a number of dice in our hand we gain instant feedback of our strength in that moment.  We feel it.  As characters progress in skill and ability, it’s immediately apparent through the number of dice.  So too is the impact of adding or subtracting modifiers.  At each moment in the game we feel our character’s chance of success (or not).  Altogether it is much more personal than a faceless target number, and as such the experience of rolling heightens our emotional attachment.

Secondly, to summarize this earlier blog post, it allows for an elegant way of handling multiple actions by a character in a turn:  for each declared action above the first, subtract one die from every test made.  This allows for a sweet differentiation between experienced and inexperienced characters while also elegantly handing movement and incidental actions.  Within this system there are no fixed silos of (arbitrarily increasing) attacks per turn, no rigid number of actions/moves/bonus actions, or the like; instead it provides a unified and organic method that promotes options, interesting choices, and crazy excitement.

Thirdly, it allows for various sub-systems and abilities (such as martial arts, stunts, equipment traits, or other similar things) where removing dice can be used to “fuel” special maneuvers or attacks.

Lastly, because we’re dealing solely with dice, both the number of calculations as well as the values involved tend to remain low.  There’s no need to add, for example, +17 to a roll.  Starting with a base number of dice (likely to be less than 10), then adding or subtracting a few dice (likely to be less than 6 either way) for modifiers keeps things simple.  Even if our list of modifiers grows large, because we are dealing with actual dice it remains easy to calculate things by going through modifiers one by one and physically adding or removing dice from our hand until the final value is reached. Continue reading

The Aurora RPG Engine – Part 2

Intentions and Advantages of the Aurora RPG Engine

  • Delightfully visceral, with an intuitively graspable chance of success and strong emotional engagement.
  • Uncomplicated and minimal math plus easy handling of modifiers makes for a quick and efficient resolution system.
  • In a clean and innovative way, outcomes generate a Margin of Success or Failure that tie both into crunchy rule impacts and/or narrative boons, banes, and effects.
  • Easy to hack and customize to suit a campaign’s specific needs in terms of genre, tone, feel, and playstyle.
  • Emphasizes player choice and agency, allowing for greater options, engagement, excitement, and storytelling oomph.

Aurora’s Core Resolution Engine Building Blocks

  • The task resolution mechanic is d6 pool system.
    • All die values in the game are written without the 6 on d6, as there are no other dice. For example: 5d.
    • Values are (generally) stepped up or down in ½d increments: 4d, 4½d, 5d, etc.
    • A ½d is a d3.
  • Values on the character sheet determine the base pool.
    • Exactly what these values are, and what they represent, varies depending on the genre, style, and tone of the campaign.
    • Most games will use a combination of values to generate the base pool.
    • Common value groupings include:
      • Attributes
      • Skills
      • Styles
      • Roles
      • Backgrounds
      • Approaches
      • Aptitudes
      • Traits/Aspects/Distinctions/Tags
    • Values are (generally) rated in ½d increments.
  • The base number of dice for a skilled entry-level professional is 5d.
    • Consider: “If this was someone’s profession, and they had a year or two in that profession, would this be considered regularly doable? Would this be in their wheelhouse?”  If so, this is the baseline of 5 dice.
    • A higher level of skill, experience, or capability is represented by a base number of dice greater than 5.
    • Likewise, a lower level of skill, experience, or capability is represented by a base number of dice less than 5.
  • This base pool is adjusted.
    • Tasks of greater or lesser difficulty are handled by adding or subtracting dice from the character’s base pool.
    • External and contextual modifiers to the task (for equipment, environment, situation, injuries, etc) are also handled by adding or subtracting dice from the character’s base pool.
    • Modifiers are (generally) applied in ½d increments.
    • Therefore, the total pool rolled (generally) equals the Base Values ± Difficulty Modifier ± All External & Contextual Modifiers.
  • The target number of the roll is 15.
    • This number is fixed; as above, tasks of greater or lesser difficulty, as well as external and contextual modifiers to the task, are handled by adding and subtracting dice from the character’s base pool, not by increasing or decreasing the target number.
  • Rolls that total or exceed the target number of 15 count as a success.
    • “Extra” dice (the number of dice remaining after totalling enough dice to equal 15) count as the Margin of Success.
    • These Margin of Success dice are then used to gain superior outcomes, including narrative favour, creating advantages, extra effect(s), etc.
  • Rolls that total less than the target number count as a failure.
    • “Extra” dice can be bought (one by one) to be rolled and added to the total to succeed “at cost” by incurring setbacks, including narrative disfavour, disadvantages, troubles, complications, etc.

Continue reading

The Aurora RPG Engine – Part 1


To begin, I’m not sure there can be a truly universal RPG system that can, or will, fit each and every RPG possible.  Every genre, sub-genre, and even playstyle within each (sub)genre is going to have its own flavour.  For example, for a campaign set in a post-apocalyptic Australia, the tone, focus, and involvement is going to be vastly different if playing in the way of Tank Girl (silly hijinks) versus playing in the way of Mad Max (amped up action/adventure) versus playing in the way of Twilight 2000 or Wasteland (gritty, minutia, perilous).  The rules of the system used for those campaigns needs to be designed to fit and support their unique flavour and to thereby draw out the specific feel of the (sub)genre.  Between each type of campaign there are going to be differences.

That said, I do believe there’s still plenty of space for a core framework that can form the foundation for these different campaign types, using customization and specific sub-systems to appropriately mold the system to fit the (sub)genre and feel of both the world and the playstyle.  Thus, creating more of a universal “toolkit” rather than a single universal “system.” Continue reading

Gaming Thursday: RPG System: The Release

It is ready!  After many years of musings and thoughts, experiments and explorations, tests and tweaks, frustrations and, I will admit, moments of wondering if this was all a fool’s errand, it has finally come together in a flurry of insights, inspirations, and a few nifty innovations.  The long journey has come to fruition – the core of my RPG system is ready for release.  And so with that, and with great excitement, I introduce you all to:



The Aurora RPG Engine.  A core resolution system that is visceral and intuitive, with a quick and meaningful resolution engine that emphasizes player choice, agency, and engagement.  In addition, it is designed with many hooks to be adjusted and customized for many different games and campaigns, suiting their needs in terms of genre, tone, feel, and playstyle while supporting both crunchy and narrative mechanics for excitement and storytelling delight.

Starting next Monday, Aurora will take over the blog for a week, interrupting the regular schedule to allow for the entire engine to be posted.  Besides the system itself there will be designer notes, greater explorations on how the various pieces fit together, peeks beneath the hood on why the engine was designed the way it was, and examples of how to use it all, adding subsystems to create a full RPG system to support a rich and exciting campaign.

I’m chuffed and giddy and just a bit nervous to share it all with you.   But I can’t wait to see what you all think and, even more so, what you do with it and the games and awesome times and stories it supports.

See you Monday!