Thursday, August 23, 2018

Putting units or actions in the outer loop ...

Many of the discussions regarding rules design in miniature wargaming involve the turn sequence, and how to structure it in order to achieve some desired effects. Over the years, there have been many different variants of the turn sequence, illustrating various schools of thoughts on how to organize the game. Often, discussions are framed as IGO-UGO vs unit-activation, but the spectrum is more varied than that. See also my earlier post on discussing various ways of looking at the turn sequence.

In this post, I will offer a slightly different way of looking at the turn sequence, and how it can affect rules design.

Action-based turn sequences

In an action-based turn sequence, the turn is defined as a (strict) sequence of actions, and within each action, every units can do exactly that action. This is best illustrated with the classic move-shoot-melee-morale sequence. First, we have the movement phase, in which all units get to move. Then we have the shooting phase, in which all units can shoot. The same goes for the melee phase and the morale phase.

In computer programming terminology, one can see such a turn sequence as 2 nested loops . An outer loop loops over all actions, and an inner loop, for each action, loops over all units doing that action:
  • for each action X (in fixed order move, shoot, melee, morale):
    • for each eligible unit Y (order usually chosen by player):
      • unit Y does action X
Such a turn sequence has a number of advantages - there is a fixed order for all actions, and this implies one can be sure that all movement has happened before shooting and melee, morale checks are performed after all combat etc. This can lead to a design in which those various phases of the turn are strongly coupled. However, it also often leads to rules in which all turn phases use separate mechanisms which have not much in common from a procedural point-of-view. The mechanisms for shooting and melee can be very different, and morale usually is a separate subsystem.

An important and crucial disadvantage is that actions which are not explicitly listed in the turn sequence cannot be added to the games engine in an elegant manner. Such actions are often defined in terms of an existing action. E.g. setting a building on fire might take half a move; or instead of fighting a unit might build (part of) a bridge. An alternative solution is to add such additional actions explicitly to the turn sequence. E.g. one can imagine having a separate "engineering phase", or "spell casting phase". The drawback is that such specialized actions become very visible in the outer loop, while relatively few units might be eligible to act on them. These actions might also be rarely used during the entire game, depending on the specific scenario. In a fantasy ruleset we used during the late 90s, there was a phase in the turn sequence called "Morph Friendly Cyclics". It always gave rise to the same joke in each and every game. "Hold on guys, we forgot the Morph Friendly Cyclics phase! Friendly cyclics anywhere? No friendly cyclics? Are you sure? Ok, now we can move on ... "

Unit-based turn sequences

In computer programming, 2 nested loops can often be interchanged. We can also do this in the turn sequence. Instead of defining the turn as a loop over all actions, we define it as a loop over all units:
  • for each unit Y (order usually chosen by player, and/or driven by an activation mechanism):
    • for each eligible action X (chosen from a list of possible actions):
      • unit Y does action X
Such turn sequences are often called unit-based activation, since the units might be activated by die rolls, cards in hand etc. There might even be a terminating condition (e.g. a failed die roll), indicating the end of the turn. When a unit is activated, there usually is a choice of what actions, or a combination of actions (perhaps expending a budget of 'action points'), can be executed with that unit.

The main disadvantage of such a sequence is that it is difficult to maintain coherency between units. E.g. if one would like to maintain a battle line, and one cannot be sure that all units can move forward during this turn (e.g. if there is a possibility not all units might get activated), this can really frustrate player or result in ahistorical behaviour of the troops on the gaming table. Often, a mechanism for activating a group of units is necessary as part of the activation procedure.

On the other hand, there is a big advantage when one wants to add additional types of actions. Since actions do not drive the turn sequence at the top-level, adding actions does not change the turn structure. Rather, actions are an add-on to an already existing structure, which makes it easier to maintain coherent procedures and game mechanisms.

This does not prevent from actions having their own disparate procedures, but it does create a structure in which a coherent mechanism for resolving actions is more viable. One of the best examples is the Basic Roleplaying System by Chaosium. It exists in many different variations (the Call of Cthulhu rulesystem probably is the best-known). Looping over the characters is the outer loop (as in most roleplaying games), and each action - whether it is searching in a library or swimming across a pond - is resolved by checking a D100 vs a target number. That results in a very elegant and tight design, and adding new types of actions is rather straightforward.

The same structure can be used in miniature wargaming. Whether you want to add engineering actions, special movement or shooting actions, or actions invented for a specific scenario only, they can be fitted much easier in the overall game structure as opposed to an action-based turn sequence.

16 comments:

  1. Another interesting Turn Sequence post, Phil!

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  2. Nicely explained and an enjoyable post to read as usual. Thanks.

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  3. +1
    very interesting, have you ever tried some "half action" turn sequence?
    like no type of action sequence but only A activate 1 piece and can move OR shoot, and so on until every player has activated all his pieces; there can be some clutter but maybe can generate some interesting situation.
    (sorry for bad english)

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    1. You mean as in every player activates a unit in turn? Yes, I have tried these, but I think they do not work that well for wargames. In a wargame, you usually want to mainatin some level of coherency between units (they all advance in line ...), which makes such a system very hard to execute a battleplan.

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    2. Great blog Phil! What do you think of including logistics points as a resource? And each unit uses action points/logistics points to perform actions? I am thinking of including that in my game as part of the advanced ruleset.

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    3. I have used that as well (action points). See also this blogpost on my other wargaming blog: http://snv-ttm.blogspot.com/2019/03/imaginations-in-42mm-13.html

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  4. Hi Phil, I'm just catching up on your excellent series of wargame design posts (since reading your early ones on dice probabilities over a year ago).

    It seems to me the systems you describe represent the ends of a spectrum. It might be worth exploring some of the hybrid systems that fall in between, for example:

    You can have an alternating unit activation system (units in the outer loop; phases in the inner loop) but with a “bookkeeping” phase at the end of each game round. This is a good time to take care of things that affect large numbers of units (such as morale or checking for supply) but don’t involve many actual choices on the part of the player.

    You can have quasi-alternating unit activation systems in which a player nominates several of his units to activate in concert, which then take their actions together in sequential phases (e.g. movement/ranged fire/close combat). This might be integrated with the command system so that, for example, only figures belonging to the same organizational unit, or perhaps a fixed number of units within a given radius of a commander figure, can be activated together.

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    1. David,

      Yes, you're right. Many unit activation systems have some sort of bookkeeping either at the start or the end of a player's turn. E.g., in my ACW house rules, all units who suffered casualties since last turn need to take a morale check at the beginning of the turn.

      Your second point touches on group activations, which I indeed think is a necessary feature in any unit activation system. Otherwise, it becomes very difficult to keep any form of coherency - although this might also depend on the period. Whether one wants to include force organization as part of that rule is a matter of style, I think. My intuition says not to do bother too much, or perhaps apply a negative modifier when units from different organizations are activated together. It also depends whether you think a proper force organization should be translated into the gaming rules, or whether it's sufficient to take it into account during initial deployment.

      And thanks for the nice comments!

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    2. Oh, no, thank you! Your posts are all great food for thought. Your design preferences seem similar to mine: keep it simple, keep it intuitive, keep it consistent. Favor fun and playability over simulation and realism. I especially like your repeated mantra of "no mechanic makes sense except in the broader context of the game."

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  5. Great post. One of my favorite rule sets is Force on Force / Tomorrows War. It has a very unusual turn sequence that allows a lot of reactions. Have you played any games with this system? What are your thoughts?

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    1. I played the systems a few years ago, but not recently. It is indeed a bit unusual, since it takes the "action loop" to its extreme, shifting between players even within the activation of a single unit (if I remember correctly). I think it would be best described in the above framework by eliminating units altogether, and simply think about actions and reactions, irrespective of specific units.

      That being said, I am not a big fan of overwatch/reaction/... systems. I can see why they are necessary in some systems, but I also think they are the result of other design issues, such as the ratio between movement and firing distances. I always thought that rules for overwatch or other reaction systems are a patch for bad design, but I've become to appreciate them when being at the core of the rules engine (and not as an afterthought as you see on some systems).

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  6. Great post, thank you for your effort Phil!

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  7. Charles Bryers21 June 2019 at 03:17

    Interesting that the main issue is coherency. Playing mostly modern commercial games (not historical) I've never really considered it. But I guess unit formation and coherency is just as applicable in modern warfare as historical. I am also not a fan of reaction heavy systems.

    What about alternate activation but with the ability to coordinate, at the cost of freedom of action. For instance:

    - If one unit is activating it can do its full suite of actions, let's say 3 actions of whatever it wants.
    - If two units coordinate and activate together, they can now only each do two actions, and perhaps not have access to the full suite of action options.
    - If three units coordinate and activate together, they can now only each do one action, with a further limited pool of actions.

    Expand or contract to match the theme, and perhaps remove the added action type limitations if it's too impeding. Thoughts?

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    1. Good thoughts. I think that whenever you have some sort of unit activation, there is the need to allow to activate in groups to maintain coherency of units. Whether that group activation comes at a cost - and what type of cost - is something that should indeed be incorporated in the game design. Some rulesets impose a die roll modifier or something similar, but indeed, restraining the type and/or number of actions one can do is a possibility as well. A very easy mechanic could be that movement range is limited when activating a group of units.

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