Friday, September 23, 2011

Combat Maneuver Type

To recap: This blog entry discussed the three Non-Player General (NPG) Character values (Aggressive, Bold, and Cautious). This blog entry linked the NPG Character values to the three Maneuver Types (Combat, Positioning, and Defensive) and the order in which those maneuvers would be selected. In this entry will focus on the Combat maneuver type, and how to further break it down to find the move the NPG should make.

When I look at possible moves to make, and try to determine which move is better (when I have a limited number of PIPs and cannot make all desired moves), I tend to look at one factor: what is the total combat advantage I will gain by making the move. What do I mean by that?

As shown in the figure above, assume that I use a PIP to move the group of two red Blade elements into contact with the two white Auxilia elements. This results in two combats to resolve: one at 5 to 3 and one at 5 to 3, modified by overlaps resulting from the previous combat (it may be a 4-3, 5-3, or 5-2, depending on who, if anyone, recoiled). As you cannot determine who will win until the dice are rolled, a simple method of calculating the combat potential is to score the combat differential of all the combats resulting from the moves.

So in the example above, the move results in two combats, each of 5-3 or +2, so the move receives a score of +4. The move below, in which two red Blade elements are moved into contact with three white Auxilia elements, results in a score of +3.

Note that if the three white elements were Psiloi, with a combat factor of 2 each, the move would be scored +5, so even though the red Blade elements are moving into a position of overlap, because of the superiority in combat it would rate higher than the first depicted.

Now this is very similar to the original scoring system with the Tactical Engine in DBAS, but the idea is to provide a series of rules of which are the "best" maneuvers and only use the scoring as a tie breaker. So, what are the best combat maneuvers?

In my mind, clearly the best combat maneuvers are (in order):
  1. Results in the destruction of the enemy element if the score is tied.
  2. Results in the destruction of the enemy element if the score is beaten.
  3. Results in the destruction of the enemy element if the score is doubled.
  4. Where the worst possible result for the enemy element is it fleeing.
  5. Where my element would be destroyed on being doubled, but the enemy element would not.
  6. Where my element would be destroyed on being beaten, but the enemy element would not.
  7. Where my element would be destroyed on being tied, but there enemy element would not.
In these cases, scoring is easy ... if all the elements in the maneuver are the same, and facing similar opposing elements. But what happens when a group maneuver results in some combats at order # 3 and some at, say, #5? Use the worst case.

That's the start of the idea. Next I will focus on Defensive Maneuvers.

Friday, September 16, 2011

NPG Character and PIP Usage

So, now that we have established that the Non-Player General (NPG) can have a Character value of Aggressive, Bold, or Cautious, and under what circumstances those values change (see last blog entry), what does each value mean.

I have always viewed the use of PIPs in DBA as for one of three reasons:
  • To maneuver into combat 1.
  • To maneuver out of combat.
  • To maneuver, but neither starting nor ending in combat.
1 Typically the maneuver is into or out of contact, but could be into or out of Bow and Artillery range and fire arc too.
For simplicity, I call these three types of maneuvers Combat, Defensive, and Positioning, respectively. These three types provide an order of precedence that can be aligned with the NPG Character into Primary, Secondary, and Tertiary choices, as shown in the table below.


Note that there is a fourth possibility for a Character value, between Cautious and Bold, which would produce the precedence of Positioning, Defensive, Combat. But I decided to set that aside for the time being.

So, now we have an order to using our PIPs. If the NPG is Cautious, all Defensive maneuvers will be considered first, with Positioning maneuvers second, and if there are any PIPs remaining, Combat maneuvers last.

The next few posts will consider each maneuver type and provide a set of rules for determining the "best" PIP use within each type, hopefully tying it back to the movement scoring entries I started back in October 2010.

Thursday, September 15, 2011

A Rule-Based Tactical Engine - NPG Character

As I indicated in the last blog entry, the mechanic of scoring possible moves then executing the one with the highest score was not only too tedious (if you carried it out to every possibility), but it failed to meet the most basic requirement of the Tactical Engine (TE): to tell you, the player, which move to make.

All of my attempts to "catalog" game elements (moves, terrain layouts, deployments, etc.) have been pretty much failures because to get them "all" it would take a very long time and when I was done, it would be too unwieldy anyway. A better approach is to gather up "just enough" and as you find a need to add another element, do so. Eventually you will get to that right balance of "enough choice" versus "too unwieldy to use". So, rather than try to finish the catalog of moves, we can use the lessons from that exercise to come up with a rules-based approach.

I still want to keep the concept that the character of the Non-Player General (NPG) changes through the course of the game as certain events occur. If the NPG is losing, he should be more cautious; if he is winning, he should be aggressive. The basic rules for determining the current character of an NPG is (in order of precedence) are:
  1. An NPG is Cautious if 3 VP have been scored against him.
  2. An NPG is Cautious if 2 VP have been scored against him, and he has scored no VP.
  3. An NPG is Bold if he has scored at least 2 VP more than has been scored against him.
  4. An NPG is Bold if he has rolled a '5' or more for PIPs this bound.
  5. An NPG is Aggressive.
These five simple rules now allow. you to gauge how aggressively the NPG will play, given the values Cautious, Aggressive, and Bold. Next post will look at how those three values affect movement selection.

Tuesday, September 13, 2011

Why the Tactical Engine "Failed"

For those that have looked at my "Tactical Engine" (TE) in De Bellis Antiquitatis Solus (DBAS) you will have noticed that I have taken a non-random approach, meaning I do not use any random elements (like dice) to resolve which move to make in favor of another. Instead, I wanted to take a "logical" approach and weight all of the options, using a scoring formula, and take the highest value move first, the second highest second, etc.

The problem with this approach is:
  1. You must determine all of the possible moves an element can make, then calculate each score to determine which to make.
  2. You must determine all of the moves all elements could make, and compare each's best score to determine which would be first.
  3. A group of n elements has, at a minimum, n number of moves (one as a group of n, one as a group of n-1, one as a group of n-2, etc. and one as a single element).
Thus, the problem with the approach is that, taken to its logical conclusion, you would spend so much time determining all the possible moves, and scoring them, that you would have no fun. Or you would do what I did and only score what you thought was the element's or group's "best" move was and go from there. And if you do that, it is really little different from the tried and true solo gamer's methodology: play each side to the best of your ability.

So, what is the purpose of the TE? Originally, it was to point you, the player, to the move to be made by an element or a group. That caused me to re-think the process. Currently you could say that my process is to:
  1. Think of all the possible moves. (Or think of all of the probable moves.)
  2. Score each of those moves.
  3. Execute the moves in order from highest score to lowest, until you run out of PIPs.
The heart of the problem here is that the TE is not telling you what moves to make, you are telling it a move and it gives you a number indicating how "good" it is. Any "better" move won't be revealed unless you think of it and score it out.

So, if you want a solo system where the Non-Player General (NPG) presents the moves to you, you need a system of movement rules where you run down the list and when a triggering condition is met, you execute the move that it indicates. A "simple" IF-THEN rule base. That is the approach I am going to use for the TE in DBAS. If that is not the approach you want for your solo gaming, you might look at Richard Lee's Solo DBA on the Solo DBA Development forum on Yahoo.

More on this subject next time.