Tuesday, May 21, 2013

Proposal for a new melee combat option: Evaluate ( combat opening )

This post is a draft of a new combat option for the Evaluate action. Initial thoughts about this was posted here.

The Serendipity Engine

Screen Shot of the alpha version on May 21st 2013


Simulate how combats are made of serendipitous opening that perceptive and skilled fighter take advantage of. One can fight according to a plan, or be nimble and go with the flow. This option provides the "flow".


A skill contest between the Per-based melee combat skill of the attacker against the DX-based melee combat skill of the defender. In case of a success by the attacker, the attacker spot a combat opening with a benefit that is a function of the margin of success. If the margin is negative, but the Per-based skill check was successful, the bonus is applied to the next active defense.

To generate interesting openings, the random "table" is implemented as a web application. This has the potential to generate over a few hundreds different combinations of opening and conditions, and this number of permutations blows up into the thousands if we take into account the range of possible attack bonuses and defense penalties.


The phasing player may call an Evaluate(combat opening) as a melee combat move. The skill contest is resolved by the app, determine the success and generate an opening. In case of failure, the phasing player my be compelled to take a Do nothing action. In other cases, the phasing player is free to take advantage of the opening by converting the evaluate into a new action and immediately resolving it to exploit the opening, or take instead a Do Nothing or All-out defense action. The gamble here is that if the opening isn't desirable, the turn will be spent looking  for an opening and deciding not to take it.

  1. Declare an Evaluate (combat Opening)
  2. Per-skill vs DX-skill (handled by app)
  3. Pick Either of:
    1. Immediately convert to attack to exploit opening.
    2. Do Nothing

A critical fail on the Per-based skill check is narrated to the player like a criticl success, but is converted instead into a bonus for the opponent as a bonus to any form of counter attacks.


This is not a new idea, if you want a low-tech table instead, try Sean Punch's post of SJG's forum, or +Douglas Cole 's post on Gaming Ballistic. We're going to playtest the idea, but this is out there is anyone else want to give it a go.  Here is what I'm looking for in a playtest:

  1. Are players using the the Evaluate (opening)?
  2. When presented with an opening, are the players deciding to exploit the opening?
    1. If not,
      1. is this because of the condition being too restrictive?
      2. is it because the bonus doesn't outweigh the limitation?
    2. If so,
      1. Did it made the combat more fun?
      2. Did it incite players to try moves that they usually don't use?
      3. Was the bonus conferred too large?
  3. Web application, a good idea or would it be better with a much simpler table (see Sean Punch's post linked above).
If you give it a try, by all means, communicate your thoughts and suggestions in the comments section below.

Next steps beyond playtesting

  • Adding openings that are more contextual:
    • rough terrain.
    • Multiple opponents.
    • Presence of allies.
    • Long reach weapons.
    • Two-handed vs one handed with shields.


  1. Really neat. A few comments:

    * I might look at a slightly different mechanic. Maybe declare an Evaluate, and on your NEXT turn, you can roll the contest as you describe. Then you can act using the opening, act some other way, or not.

    * If you want to do Evaluate and Attack in one turn, roll at -6, just like a Rapid Strike.

    * I think it would be really cool if along with an opening, there's a corresponding "closure." So your foe is open to a low-line grapple (-2 to defend), but all high-line strikes might be at +2 to defend. High line grapples and low-line strikes are unchanged.

    * Very particular note about one grappling result I saw, with a +1 to your ability to grapple. That won't help on a grapple based on an attack/defense, in my experience. You want to penalize your foe's ability to actively defend if you want this opening to be exploited. That's the rate-limiting step to convert to success here.

    1. Tahnks Douglas,

      1) Not sure about the best mechanic, this can be tried many different ways. Trying out will tell.

      2) Closures could be implemented without too much trouble. Making pairs of openings/closures that make sense together would be a bit more work, but doable.

      3) I've already changed the modifier code to favor the penalty to defense instead of bonus to Hit. I think that the opening should be more slanted to a defense penalties, after all.

  2. Would a GM ever consider using Evaluate against the PCs?

    1. What is good for goose is good for gander. Putting on a full face helmet comes at a cost that I doubt is worth the DR.

    2. How would a full face helm hurt you? It might make it hard for you to make a Per roll, but it won't make your DX-based roll not to have an opening any lower.

    3. It makes it harder to see opening. But yea, it wouldn't make a difference in keeping opening closed for you.

  3. I'm a little unsure how this is generated. It seems like, lacking the app, I can't use this rule. It's app or nothing, which isn't something I'm pre-disposed to like in a rule.

    The weird thing is, and one I know my players would moan about, is that the opening isn't really "there" unless you've got the Per to spot it. And nothing they do with their character allows them to, say, especially shield their weapon, counter observation, not expose what the app says you've exposed, etc.

    Plus, there are some odd results:

    "Nothing's open!

    No Opportunity observed, Do Nothing for this turn"

    Okay, so I get this result - I can't convert to an immediate attack. I just "Do Nothing." Even the tiniest chance of that means my players won't try this, because almost anything is better than Do Nothing.

    Or "You spotted a vulnerability on yourself, you may close it and apply your bonus to the next active defense in this turn if you end your turn within your opponent's main weapon reach

    Bonus to You: 1"

    What if I back out of his reach, I lose my bonus? That seems . . . odd.

    I think this is going to take a little testing. ;)

    1. Thanks Peter,

      A normal evaluate gives up to +3 in 3 turns. This evaluates gives about 3 points worth of modifier, but not all turns. Sometime, when the opponent is better at keeping his side tight that you are at spotting openings, the second just goes by. In the end, the average benefit per unit's time is the same.

      It abstracts minute movements: the defender tries its best to keep everything protected, but its going to be as good as its weapon skill. We can't simulate every single body motion: the process returns something out of sort when it is spotted.

      That it is tied to an app, I can see you point. Making a table to capture everything would be incredibly tedious and I wouldn't use it. Hitting a screen once and get something seems more usable. We can always detail more clearly what it does, but we're not sure whether things will remain as they are for now...

      Oddness in results can be sorted out initially by asking for a reroll (the right button). We are shutting down clunky combinations as we find them. However, in the case that you mention, I'd claim that the defensive position depend on the relative position of both foes and their gears: you move ou of the way and lose this opportunity.

      Testing will tell. if the idea is good, it'll stick.