D20 Mechanic Inspired by M&M and the Apocalypse

For a long time I’ve struggled to create my own game mechanic, to no fruit (good tasting fruit, at any rate). Then it struck me: why not start with my all-time favorite game system (Mutants and Masterminds) and add my favorite game mechanic (roll results in games that are Powered by the Apocalypse).

One Caveat: I wanted the feeling of the game to be one of contests, because that’s the wheelhouse I’ve been playing in lately. What I mean by that is players and GMs (or other players) roll dice against each other to determine the winner.

Here’s what I have in mind:

  • Determine actions for PCs and, if appropriate, any relevant NPCs involved.
  • Roll 1d20+mod for the PC, and 1d20+mod for the obstacle/NPC. The winner succeeds at their stated action and gets to narrate what happens.
  • Add the loser’s resistance to their result. If the total is still lower than the winner’s result, the winner succeeds fully. If the total is higher, the winner succeeds at a cost.

“At cost” means that the loser gets to embellish on the narrative and create a minor effect (lowest degree possible).

As a general mechanical concept for a game which focuses on delivering an old school feel (mechanical simulation) with a new game experience (“story forward,” no initiative, etc.), what do you think of this?


  1. So there’s two numbers: each participant’s modifiers (including ability, gear, whatever), and a separate “resistance” score? Is there a clear dividing line for what goes into the original roll’s modifiers, and what counts as resistance? Armor, skills, saving throws, etc.?

    So the winner gets to narrate “X happens”, and the loser gets to tack on “…and/but Y” if his resistance + roll would have let him win?



    1. Pretty much, yeah.

      Right now, I’m thinking in terms of M&M stats. You have your abilities (Strength, Agility, Fighting, etc.) and your Resistances (derived from your abilities).

      So, if you were fighting hand-to-hand, you would roll 1d20+Fighting and your opponent would add their Toughness resistance to whatever they rolled if they failed (note that it doesn’t necessarily have to be Fighting if they are trying to do something else).

      If I go further with this, I’ll likely change all the stats to be more active (the ones that are rolled) and reactive (the ones that add). Example active stats might be Strength, Agility, Intellect, Charisma. Example reactive stats might be Fortitude, Perception, Reflexes, and Will. (Off the top of my head.)

      The winner gets to narrate what happens, and probably creating a mechanical effect (if dealing damage or whatnot). If the loser’s resistance pushed their roll over the winner’s result, they get to add an embellishment of the winner’s narration with a caveat that it cannot change what the winner narrated, but can work around it (“You haven’t beaten me. You sacrificed sure-footing for a killing stroke.”)

      So, yeah. Pretty much “…but, Y.”



      1. Most players probably prefer getting to say “X” over getting to tack on “Y”. Will players have any incentive to invest in resistance stats? Is doing so even possible, or are they intended to all be calculated, computed, situational, etc.?

        Are the declarations you can do with “but Y” intended to shut down further actions from the winner that amount to “I want to do X again”? For example, I shoot you with an arrow, and X is “it hits” and your Y is “but my armor soaks it”. Can I shoot you again, and we just keep tossing dice until you lose? Is this desirable?

        I’m interested to see how it plays out. For me, the make-or-break would be how powerful your “but Y” counter-declarations are allowed to be, and what kind of mechanical weight (if any) comes with them.


      2. There are two things I’m considering in making resistances worthwhile.

        1. You get to create a complication for the winner. It’s not necessarily an effect, like damage, but it will limit your opponent’s future actions.

        2. The winner’s degree of success (damage, etc.) is calculated based on how his overall scored against your resistance. So you want it high.

        For instance, on an attack roll, you end up with two results 22 and 18 (+Resistance 5 = 23). The 22 wins and describes and effect, the loser gets to embellish and put the winner in a bad spot (giving the loser here a benefit in the next roll?). Then the winner calculates damage conditions dealt, which has a base related to weapon, then modified by degree scored.

        The degrees I have in mind are: Fails to overcome resistance (1st degree), overcomes resistance (2nd degree), overcomes resistance by 5+ (3rd degree).


  2. I really like this as a four way result matrix. Simple, elegant. A lot is going to depend on the numbers for mods and resistance of course. Maybe a default resistance at half the modifier?



    1. I played some very quick rolls with this, and it went surprisingly fast. It ended up being:

      Roll two dice (+mod) to determine winner. Add a second number to one of them. Figure out the degree of success. Narrate.

      The actual math behind it…I’m being purposely vague at the moment because math is usually where I get distracted from the game experience. It’ll certainly be an ordeal pretty soon, however.



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